V3 Use EXIF byte order for EXIF encoded strings.

[JimBobSquarePants]

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Description

Fixes #2906

A backport of #2943 for V3.

[Copilot]

Pull Request Overview

This pull request backports changes to ensure that EXIF encoded strings are interpreted using the EXIF byte order. Key changes include:

• Addition of a new test case for Issue2906.
• Updates to ExifEncodedString and ExifEncodedStringHelpers to handle a ByteOrder parameter.
• Adjustments to ExifReader and ExifTag for improved endianness management.

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/Images/Input/Webp/issues/Issue2906.webp	Adds a new Git LFS pointer file for testing.
tests/ImageSharp.Tests/TestImages.cs	Registers the new test image constant.
tests/ImageSharp.Tests/Formats/WebP/WebpDecoderTests.cs	Introduces a new test verifying proper decoding for Issue2906.
src/ImageSharp/Metadata/Profiles/Exif/Values/ExifEncodedString.cs	Adds a ByteOrder overload for TrySetValue and defaults to LittleEndian in the parameterless override.
src/ImageSharp/Metadata/Profiles/Exif/Tags/ExifTag.cs	Updates equality operators to handle nullable values.
src/ImageSharp/Metadata/Profiles/Exif/ExifReader.cs	Refactors endianness handling, ensuring ByteOrder is set based on IsBigEndian.
src/ImageSharp/Metadata/Profiles/Exif/ExifEncodedStringHelpers.cs	Updates methods to accept and use ByteOrder, with BOM detection logic for Unicode.

Comments suppressed due to low confidence (2)

src/ImageSharp/Metadata/Profiles/Exif/ExifEncodedStringHelpers.cs:105

• Consider parameterizing or deriving the ByteOrder for GetDataLength to reflect the actual EXIF byte order, rather than defaulting to LittleEndian.

(uint)GetEncoding(encodedString.Code, ByteOrder.LittleEndian).GetByteCount(encodedString.Text) + CharacterCodeBytesLength;

src/ImageSharp/Metadata/Profiles/Exif/ExifEncodedStringHelpers.cs:112

• Consider using the actual EXIF byte order for encoding the string in Write, instead of hardcoding LittleEndian, to ensure consistency with the rest of the EXIF handling.

int count = Write(GetEncoding(encodedString.Code, ByteOrder.LittleEndian), text, destination[CharacterCodeBytesLength..]);