feat(ws): allow to use upgradeWebSocket in handler

[nakasyou]

Closes #3005, and related to #3202 and #3845.

By the pull request, you would use upgradeWebSocket after return in handler like that:

const app = new Hono()

app.get('/', (c) => {
  return upgradeWebSocket(c, {
    onOpen: (_e, ws) => {
      ws.send('Hello World!')
    }
  })
})

A thing what I will be glad is c.req.param will be type-safe.

Also bindings and variables are supported.

const app = new Hono<{
  Bindings: {
    DB: {
      insert: (v: string | Blob | ArrayBuffer) => void
    }
  }
}>()

app.get('/:room', (c) => {
  return upgradeWebSocket(c, {
    onMessage(e) {
      c.env.DB.insert(e.data)
    }
  })
})

The author should do the following, if applicable

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.30%. Comparing base (a2ec848) to head (3265bb7).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3942      +/-   ##
==========================================
- Coverage   91.32%   91.30%   -0.03%     
==========================================
  Files         168      168              
  Lines       10688    10786      +98     
  Branches     3070     3103      +33     
==========================================
+ Hits         9761     9848      +87     
- Misses        926      937      +11     
  Partials        1        1              

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[yusukebe]

Hey @nakasyou

This is a good idea! I like this approach. Please check the comment I left.

[nakasyou]

Hi @yusukebe, I fixed the code from your review. Could you check it?