Make WebSocketService.MaxTextFrameSize configurable

[d-eggert]

Is your feature request related to a problem? Please describe.
We use the websocket interface to pulsar. Our current use case demands the transmission of big messages (10MB or even more), which is not possible due to the hardcoded limit in WebSocketService

Describe the solution you'd like
Make this value configurable, e.g. via websocket.conf

Describe alternatives you've considered
Maybe increase the hardcoded default.

Additional context
None.

[zhanghaou]

Thanks for your feedback, I will fix it.