Add Reset() to the Zlib-based Encoders/Decoders

[iremyux]

Implements #130465

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[Copilot]

Pull request overview

Adds Reset() support to the zlib-based streamless encoders/decoders in System.IO.Compression so instances can be reused for independent compression/decompression operations, backed by a new native deflateReset export and expanded test coverage.

Changes:

• Add native CompressionNative_DeflateReset export and managed LibraryImport wrapper plumbing.
• Add public Reset() APIs to Deflate*, ZLib*, and GZip* encoder/decoder types and route them to zlib reset functionality.
• Enable and extend shared encoder/decoder tests to validate reset semantics (no-op on fresh instance, reset after partial work).

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/native/libs/System.IO.Compression.Native/System.IO.Compression.Native.def	Exports the new native CompressionNative_DeflateReset symbol on Windows.
src/native/libs/System.IO.Compression.Native/System.IO.Compression.Native_unixexports.src	Exports the new native CompressionNative_DeflateReset symbol on Unix.
src/native/libs/System.IO.Compression.Native/pal_zlib.h	Declares the PAL entrypoint for CompressionNative_DeflateReset (with documentation).
src/native/libs/System.IO.Compression.Native/pal_zlib.c	Implements CompressionNative_DeflateReset via deflateReset.
src/native/libs/System.IO.Compression.Native/entrypoints.c	Adds CompressionNative_DeflateReset to the resolver table for LibraryImport.
src/libraries/Common/src/Interop/Interop.zlib.cs	Adds LibraryImport for CompressionNative_DeflateReset.
src/libraries/Common/src/System/IO/Compression/ZLibNative.cs	Adds ZLibStreamHandle.DeflateReset() wrapper on the SafeHandle.
src/libraries/System.IO.Compression/src/System/IO/Compression/DeflateEncoder.cs	Adds public Reset() that calls into DeflateReset and clears managed finished state.
src/libraries/System.IO.Compression/src/System/IO/Compression/DeflateDecoder.cs	Adds public Reset() that calls InflateReset2_ and clears managed finished state.
src/libraries/System.IO.Compression/src/System/IO/Compression/ZLibEncoder.cs	Adds public Reset() delegating to the underlying DeflateEncoder.
src/libraries/System.IO.Compression/src/System/IO/Compression/ZLibDecoder.cs	Adds public Reset() delegating to the underlying DeflateDecoder.
src/libraries/System.IO.Compression/src/System/IO/Compression/GZipEncoder.cs	Adds public Reset() delegating to the underlying DeflateEncoder.
src/libraries/System.IO.Compression/src/System/IO/Compression/GZipDecoder.cs	Adds public Reset() delegating to the underlying DeflateDecoder.
src/libraries/System.IO.Compression/ref/System.IO.Compression.cs	Adds the new public Reset() members to the public surface area.
src/libraries/Common/tests/System/IO/Compression/EncoderDecoderTestBase.cs	Adds reset-focused tests to the shared encoder/decoder test base.
src/libraries/System.IO.Compression/tests/ZLibEncoderDecoderTestBase.cs	Enables reset tests for zlib-based test suites (SupportsReset => true).
src/libraries/System.IO.Compression/tests/DeflateEncoderDecoderTests.cs	Updates adapters to forward Reset() to DeflateEncoder/DeflateDecoder.
src/libraries/System.IO.Compression/tests/GZipEncoderDecoderTests.cs	Updates adapters to forward Reset() to GZipEncoder/GZipDecoder.
src/libraries/System.IO.Compression/tests/ZLibEncoderDecoderTests.cs	Updates adapters to forward Reset() to ZLibEncoder/ZLibDecoder.

[Copilot]

Pull request overview

Copilot reviewed 19 out of 19 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

src/libraries/System.IO.Compression/ref/System.IO.Compression.cs:27

• This PR adds new public API surface (e.g., DeflateDecoder.Reset() and similar Reset() methods on other encoders/decoders), but the linked issue (#130465) is only labeled api-ready-for-review and does not have the required api-approved label. Per the API approval process, new public APIs should not be implemented/merged until an approved API shape is available and linked.

Please complete API review/approval (issue gets api-approved and an approved API shape comment), then verify the ref/ changes match that approved shape; or, if approval is pending, keep these APIs out of ref/ (and out of public surface) until approval is granted.

    public sealed partial class DeflateDecoder : System.IDisposable
    {
        public DeflateDecoder() { }
        public System.Buffers.OperationStatus Decompress(System.ReadOnlySpan<byte> source, System.Span<byte> destination, out int bytesConsumed, out int bytesWritten) { throw null; }
        public void Dispose() { }
        public void Reset() { }
        public static bool TryDecompress(System.ReadOnlySpan<byte> source, System.Span<byte> destination, out int bytesWritten) { throw null; }

[rzikm]

LGTM once API is approved