feat(serve-static): "206 Partial Content" support

[exoego]

Closes #3324

This implements 206 Partial Content(also called as range requests) support in serve-static middleware. It will be useful specially for seeking a video file.

serve-static base implementation now accepts an optional function:

partialContentSupport?: (path: string) => Promise<{
      size: number
      getPartialContent: (start: number, end: number) => PartialContent
      close: () => void
}>

If partialContentSupport is provided and HTTP header includes valid Range, serve-static returns subsets of content. getPartialContent function encapsulates a file handle to avoid opening and closing file multiple times. close function is invoked when all ranges are read, to teardown the file handle.

416 Range Not Satisfiable

The implementation also returns 416 Range Not Satisfiable if Range headers contains many range requests (more than 10), that is potentially DoS (Denial of Service) attack. This limitation (10) is just a clueless number. The number may be changed when we understand it is too small/too big.

Not included

• Cache-control via If-Range, ETag and so on. I think this feature is useful without having cache-control, which needs a lot work.
• Node.js implementation. Because Node.js does not share serverStatic implementation 😭 It is solely implemented here: https://github.com/honojs/node-server/blob/74e86a28f375e5acd52e342519ff2b1110a95c16/src/serve-static.ts#L59
• Deno coverage is 0%: #3456 will fix it

The author should do the following, if applicable

• [x] Add tests
• [x] Run tests
• [x] bun run format:fix && bun run lint:fix to format the code
• [ ] Add TSDoc/JSDoc to document the code

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 82.65896% with 30 lines in your changes missing coverage. Please review.

Project coverage is 95.36%. Comparing base (f1ec415) to head (07b6334). Report is 217 commits behind head on main.

Files with missing lines	Patch %	Lines
src/adapter/deno/serve-static.ts	0.00%	24 Missing :warning:
src/adapter/bun/serve-static.ts	81.81%	6 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3461      +/-   ##
==========================================
- Coverage   95.58%   95.36%   -0.22%     
==========================================
  Files         155      155              
  Lines        9357     9524     +167     
  Branches     2746     2776      +30     
==========================================
+ Hits         8944     9083     +139     
- Misses        413      441      +28     

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[yusukebe]

Hi @exoego

I'm sorry I can't review it yet. Still a little bit busy; please wait.

[yusukebe]

@exoego

I'm sorry for being super late. I have an idea, and I'll share it with you soon.