feat: allow enabling and disabling compression and decompression separately

[Aeolun]

This splits out the keys for enabling decompression and compression. I basically wanted to use the library to decompress incoming requests only, but got free compression for my trouble (which caused the issue that I had in the other PR I submitted).

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[mcollina]

lgtm

[Eomm]

Could you run npm run lint:fix?

[Aeolun]

@Eomm Yeah, hadn't realized I didn't do so until I saw the PR complaining about it. Hopefully good now.

[gurgunday]

lgtm

[Copilot]

Pull Request Overview

This PR enables separate control of compression and decompression functionality by introducing new configuration options globalCompression and globalDecompression. Previously, the single global option controlled both features together.

• Adds globalCompression and globalDecompression options that fall back to the existing global option when not specified
• Updates both compression and decompression parameter processing to respect the new separate flags
• Documents the new configuration options with usage examples

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 1 comment.

File	Description
index.js	Modifies parameter processing logic to check new global flags before falling back to existing global option
README.md	Adds documentation and example for the new globalCompression/globalDecompression configuration
test/global-compress.test.js	Adds comprehensive test coverage for the new separate compression/decompression control functionality

Comments suppressed due to low confidence (2)

test/global-compress.test.js:344

• The zlib module is used but not imported in this file. Add 'const zlib = require('zlib')' at the top of the file.

  test('using gzip when `Accept-Encoding` request header is `gzip`', async (t) => {

test/global-compress.test.js:430

• The zlib module is used but not imported in this file. Add 'const zlib = require('zlib')' at the top of the file.

    const payload = zlib.gunzipSync(response.rawPayload)

[Copilot]

[nitpick] The example shows only disabling compression but the comment mentions 'only decompress'. Consider showing both options or clarifying that globalDecompression defaults to true.

Suggested change

	// only decompress compressed incoming requests
	{ globalCompression: false }
	)
	// Disable compression but keep decompression enabled (default behavior for globalDecompression is true)
	{ globalCompression: false }
	)
	// Disable decompression but keep compression enabled
	await fastify.register(
	import('@fastify/compress'),
	{ globalDecompression: false }
	)