Add support for HTTP 2.0

[VigneshVSV]

Since HTTP 3.0 is already under discussion & HTTP 2.0 seems to be stable, we want to add support for HTTP 2.0

Steps involved:

• Check tornado's HTTP 2.0 implementation, I made a fork which fixes a bug (https://github.com/VigneshVSV/tornado_http2), merge it back to tornado and get their latest commits
• If tornado is not stable, find another async provider, how about fastapi?
• Implement Property, Action and Event Handlers and all other handlers necessary
• Add option to user to choose the HTTP server and its version
• Also add support of previous point to the to run_with_http_server method of Thing class
• Test informally or write tests. If possible, get some numbers regarding the performance in a comparative manner

Either package it with our release or add to pip dependency in requirements.txt