Add missing encodings to TextDecoder

[Jarred-Sumner]

What does this PR do?

This pulls in implementations of all the text encodings from WebKit for TextDecoder.

Fixes #11564
Fixes #10696

TODO before merging:

• Copy some of the WPT for these text encodings

How did you verify your code works?

A couple small tests.

[robobun]

^{Updated 6:22 PM PT - Jan 8th, 2025}

❌ @Jarred-Sumner, your commit 6edb3f4 has 1 failures in #9277:

• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 20.04 aarch64
• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 12 aarch64
• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 24.04 aarch64
• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 22.04 aarch64
• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 20.04 x64-baseline
• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 22.04 x64-baseline
• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 12 x64
• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 12 x64-baseline
• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 22.04 x64
• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 24.04 x64-baseline
• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 24.04 x64
• test/js/web/encoding/text-decoder-shiftjis.test.ts - SIGABRT on 🐧 20.04 x64

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🧪   try this PR locally:

bunx bun-pr 13959

[kuromiii]

Any update on that PR? Would love shift-jis support added to TextDecoder as I need it for one of my projects :)