Enhance typing feedback

[matevskial]

Hello, I discovered you on Youtube and checked your Github repository, thought I might contribute with some ideas.

This PR makes some enhancements to the typing feedback mechanism: The changes include:

• introduce new socket event "stop-typing"

• send "stop-typing" socket event when the user focuses of the message field

• send "stop-typing" socket event when the user stops typing in the message field for a second

I am doing this PR for exercise purposes, would be awesome to hear back from you with some constructive criticism when/if you have time.

[ForrestKnight]

This looks good as well, but appears to have conflicts because I merged your previous PR.

[matevskial]

Merge conflicts resolved.

I think they appeared because I added new stuff in the existing lines of code instead at the bottom of the file.