feat(hono/context): add buffer returns #6109

Job	Run time
Bun	6s
Fastly Compute	1m 3s
Deno	12s
Checking if it's valid for JSR	12s
AWS Lambda	1m 1s
Lambda@Edge	1m 5s
Main	1m 58s
Node.js v18.18.2	1m 10s
Type & Bundle size Check on Main	0s
Node.js v20.x	1m 1s
Type & Bundle size Check on PR	1m 13s
workerd	1m 6s
Node.js v22.x	1m 3s
Coverage	8s
	11m 18s

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