Protocol Buffers 31.0

What's new in this version:

Bazel:
- Loosen py_proto_library check to be on the import path instead of full directory (i.e. excluding external/module-name prefix)

Compiler:
- Add support for import option for protoc
- Add notices.h with information about our dependencies' licenses and add --notices flag to protoc to print the contents of that file
- Move upb minitable code generator into protoc
- Upgrade abseil-cpp to 20250127 and use @com_google_absl -> @abseil-cpp and com_google_googletest -> @googletest canonical BCR names

C++:
- Remove fast-path check for non-clang compilers in MessageCreator
- Add missing include
- Add weak attribute to GetClassData to speed up clang builds
- Add nontemporal software prefetcher to repeated ptr field dtor to improve performance
- Warn on unused RepeatedPtrField
- Add notices.h with information about our dependencies' licenses and add --notices flag to protoc to print the contents of that file
- Fix a bug in handling of implicit-presence string_view fields
- Control bounds checks via BUILD flags
- Upgrade abseil-cpp to 20250127 and use @com_google_absl -> @abseil-cpp and com_google_googletest -> @googletest canonical BCR names
- Create hardened versions of Get and Mutable for repeated_field

Java:
- Add weak attribute to GetClassData to speed up clang builds
- Use ProtobufToStringOutput to control the output format of AbstractMessage.Builder.toString
- Implement Protobuf Java Immutable API nest_in_file_class feature for Edition 2024
- Introduce a Generated annotation to eventually replace javax.annotation.Generated (31e57fc)
- Add volatile to featuresResolved (9e03ca5)
- Fix Java concurrency issue in feature resolution for old <=3.25.x gencode using lazy feature resolution
- Remove Java runtime classes from kotlin release
- Split maven dependencies into dev vs local
- Improve error messaging when detecting and erroring out on integer overflow of byte count limit variables

Kotlin:
- Remove Java runtime classes from kotlin release

Csharp:
- Remove "experimental API" warnings from members in the .NET protobuf runtime
- Improve performace of repeated packed fixedSize fields

Objective-C:
- [ObjC] Deprecate GPBFieldDescriptor.isOptional
- [ObjC] Raise the library version and enable new generated code

Rust:
- Cherry-pick Rust fix to 31.x
- Add upb_Map_GetMutable API to upb
- See also UPB changes below, which may affect Rust.

Python:
- Update GetCurrentTime to use datetime.datetime.now (01b154c)
- Make Py JSON float_precision apply to both float and double fields
- -Add '+' and '-' annotations for Timestamp and Duration in Python (fff783e)
- Bug fix for FieldMask.MergeFrom() with unset fields
- Make python text_format able to skip unknown fields for repeated messages
- Fix segment fault for UPB Pyhon 'in' method of empty repeated extensions
- Fix upb to escape DefinitelyNeedsEscape (like " and ') for bytes field
- Check with fallback descriptorDB for FindExtensionByNumber()/FindAllExtensions in UPB python pool
- Add clear() method to repeated fields in Python
- Register Scalar/MessageMapContainerTypes as virtual subclasses of (9a0b591)
- Fix python codegen crash when C++ features are used
- Add more detail to the comment for GetMessageClassesForFiles (9befb58)
- Add constructing unpack routine to Python Protobuf Any API
- Implement typing for proto Timestamp/Duration assignments

PHP:
- Deprecate Descriptor Label. As an alternative, add helper methods for checking whether a field is required or repeated
- Feat(php): improve return typehint when repeatedfield

PHP C-Extension:
- Automated rollback of commit f9863df
- Deprecate Descriptor Label. As an alternative, add helper methods for checking whether a field is required or repeated
- Ruby: Allow to get a file descriptor by a file name
- Feat(php): improve return typehint when repeatedfield
- See also UPB changes below, which may affect PHP C-Extension.

Ruby:
- Fix silent failure of rb_test rules to run test
- Ruby | Add support for a protobuf debug build
- Ruby | Support installing the gem via git and some other small build tweaks
- Deprecate Descriptor Label. As an alternative, add helper methods for checking whether a field is required or repeated
- [Ruby]Implement #to_hash for message classes
- Drop Ruby 3.0 (5de7c80)
- Fixes #18726 by backslash escaping descriptor data containing # if the hashmark appears immediately before any of $, {, or @
- Ruby: Allow to get a file descriptor by a file name
- Ruby: fix bug in Map.hash

Ruby C-Extension:
- Ruby | Add support for a protobuf debug build
- Deprecate Descriptor Label. As an alternative, add helper methods for checking whether a field is required or repeated
- Ruby: Allow to get a file descriptor by a file name
- Ruby: fix bug in Map.hash
- See also UPB changes below, which may affect Ruby C-Extension

UPB (Python/PHP/Ruby C-Extension):
- Fixed LTO-only linker error in upb linker arrays
- Deprecate Descriptor Label. As an alternative, add helper methods for checking whether a field is required or repeated
- Add upb_Map_GetMutable API to upb
- Fix upb to escape DefinitelyNeedsEscape (like " and ') for bytes field
- Upb: delete functions in map_gencode_util. They're unused after the Map iterator API change
- Upb: Update _upb_map_next signature to return a boolean and remove the _nextmutable Map iterator API
- Change upb C generated map iteration function to not hand out MapEntry pointers
- Ruby: Allow to get a file descriptor by a file name
- Expose the upb_ByteSize function to upb clients. Note that the current naive implementation is no more efficient than serializing the message yourself and noting the resulting size
- Move upb minitable code generator into protoc
- Tolerate message set extensions encoded as normal deliminited submessages
- Automated rollback of commit 6bde8c4
- Fix UPB fast table build

Other:
- Patch rules_ruby to apply neverlink = True to the jars rule
- Restore JDK8 compatibility in Bazel for libraries with dependencies from Maven (e.g. //java/util) (e8edc5d)
- Protobuf: add //:go_features_proto Bazel alias
- Fixes -lpthread problem when building with android_arm64 config