fix(fetch): support `Content-Encoding` response header

[mikicho]

• Fixes #446
• Related to #575

Added failing test.

@kettanaito

1. At first, I thought to adopt Nock's implementation (inspired by undici), but IIRC, interceptors is cross-platform and AFAIK zlib does not exist in the browser. How does the browser decompress the response body? Am I missing something?
2. From what I see, IncomingMessage does not decompress the response body, and Node.js leaves this for the HTTP libraries (Axios, got, etc.). So, I think we should follow this behavior and leave the response body compressed.

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Summary

• We are not reusing Undici's decompression logic directly because that'd mean redistributing Undici alongside Interceptors.
• We are using Compression Streams API to decompress GZIP and Deflate both in Node.js and the browser.
• We are using zlib and a custom transform stream to support Brotli decompression in Node.js.
• We are ignoring Brotli in the browser due to WASM issues.