feat: enhanced turbo-train-stream-source JS API

[timaramazanov]

Description

Added next public JS API:

• init method - allows to init EventSource
• destroy method - allows to destroy EventSource
• state getter - returns humanized version of EventSource.readyState
• no-turbo-stream param - to not call Turbo.connectStreamSource when it's not needed

Added proxy for EventSource events:

• open
• message
• error
  So client JS doesn't need to access private #eventSource field.

Didn't implement reconnection logic inside component - as reconnection strategy might vary from case to case.

An example of reconnection strategy on client side:

onStreamError(event) {
      const error = event.detail
     console.log('An error occurred while attempting to connect to the Live Chat.', error)

      if (event.target.state !== 'open') {
        event.target.destroy()
        this.reconnectStreamTimer = setTimeout(() => {
          event.target.init()
          console.log('Attempting to reconnect to the SSE stream.')
        }, 5000) 
      }

Side fix

Remove node_modules from version control