fix: Fix bugs in new webserver

[kuznetsss]

For #919.

Fixes bugs for new webserver:

• Unhandled exception when closing already closed websocket
• No pings for plain websocket connection
• Server drops websocket connection when client responds to pings but doesn't send anything

Also changing API of ng connections. Now timeout is set by a separate method instead of providing it for each call.

[codecov]

Codecov Report

Attention: Patch coverage is 58.46154% with 27 lines in your changes missing coverage. Please review.

Project coverage is 71.92%. Comparing base (b53cfd0) to head (1bc6f7f).

Files with missing lines	Patch %	Lines
src/web/ng/impl/ConnectionHandler.cpp	17.64%	0 Missing and 14 partials ⚠️
src/web/ng/impl/HttpConnection.hpp	52.94%	2 Missing and 6 partials ⚠️
src/web/ng/Server.cpp	0.00%	0 Missing and 3 partials ⚠️
src/web/ng/impl/WsConnection.hpp	92.85%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1780      +/-   ##
===========================================
- Coverage    71.96%   71.92%   -0.04%     
===========================================
  Files          297      297              
  Lines        12775    12805      +30     
  Branches      6548     6564      +16     
===========================================
+ Hits          9193     9210      +17     
+ Misses        1845     1842       -3     
- Partials      1737     1753      +16     

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