Abseil LTS 20250512.1

What's New:

• The polyfill types absl::any, absl::optional, and absl::variant are now aliases for std::any, std::optional, and std::variant in all builds. (Note that the polyfill implementation absl::string_view remains at the present time, but it defaults to being an alias std::string_view in all builds.)
• Added absl::FastTypeId<Type>(), which evaluates at compile-time to a unique id for the passed-in type.
• Added absl::endian and absl::byteswap polyfills (25bce12).

Breaking Changes:

• Abseil now requires at least C++17 and follows Google's Foundational C++ Support Policy. See this table for a list of currently supported versions compilers, platforms, and build tools.
• Nullability template types are deprecated and will be removed in a future release. The macro-style annotations (absl_nonnull, absl_nullable) should be used instead (caf854d).

Known Issues

• None known at this time.

Baseline: bc257a8
Cherry-pick: 76bb243 (Patch 1)