feat(etag): allow for custom hashing methods to be used to etag #6216

Job	Run time
Fastly Compute	46s
Deno	12s
Bun	12s
Checking if it's valid for JSR	11s
AWS Lambda	47s
Lambda@Edge	46s
Main	1m 51s
Node.js v18.18.2	49s
Node.js v20.x	46s
Type & Bundle size Check on Main	0s
Type & Bundle size Check on PR	55s
Node.js v22.x	47s
workerd	52s
Coverage	12s
	9m 6s

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