feat(fetch): add zstandard decompression support

[J3m5]

This relates to...

Closes #2847

Changes

• lib/web/fetch/index.js: Added a condition in onHeaders to handle the zstd content-encoding header.
• test/fetch/encoding.js: Added a test case for zstd decompression.

Features

Adds support for Zstandard (zstd) decompression in fetch.

Status

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• Tested
• Benchmarked (optional)
• Documented
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• In review
• Merge ready

[mcollina]

lgtm

[J3m5]

Just saw your comment, thanks!

I've amended the last commit to add two more test cases to match the ones for gzip and brotli:

• should handle no content response with zstandard encoding
• should handle not modified response with zstandard encoding

[KhafraDev]

The tests should be added to test/fetch; test/node-fetch is taken from node-fetch.

[J3m5]

@KhafraDev I noticed the other encoding tests (like gzip and brotli) are in test/node-fetch, so I followed that pattern.

Would you prefer I move all of them into the test/fetch folder instead?

[J3m5]

@KhafraDev Ah, I see now, test/node-fetch contains tests from the node-fetch library.

Thanks for the clarification. I’ll move the new test cases into the test/fetch folder instead.
Should I put it in the encoding.js file?

[J3m5]

@KhafraDev I've moved the main test to test/fetch/encoding.js and removed the others from test/node-fetch.
Let me know if this works for you.

[bjohansebas]

LGTM

[J3m5]

@KhafraDev I applied your suggestion

[mcollina]

lgtm