Web server refactor

[cindyyan317]

1 Separate web server with RPC. Web server becomes more generic.
2 Expand the WsBase to ConnectionBase, both RPC Executor and SubscriptionManager will send the response via ConnectionBase.
3 Add unittests
4 Add some logs

[codecov]

Codecov Report

Merging #667 (91764cf) into develop (5d2c079) will increase coverage by 0.86%.
The diff coverage is n/a.

❗ Current head 91764cf differs from pull request most recent head f77e2b1. Consider uploading reports for the commit f77e2b1 to get more accurate results

@@             Coverage Diff             @@
##           develop     #667      +/-   ##
===========================================
+ Coverage    30.23%   31.09%   +0.86%     
===========================================
  Files          140      149       +9     
  Lines         7436     7892     +456     
  Branches      4422     4683     +261     
===========================================
+ Hits          2248     2454     +206     
- Misses        3109     3145      +36     
- Partials      2079     2293     +214     

see 23 files with indirect coverage changes

[godexsoft]

Leaving a few comments 👍
Overall looks good but needs a few tweaks here and there:

1. remove most one line comments that are straight up useless and/or come from examples of asio
2. Use doxygen comments to document what member functions do as well as on top of classes to briefly describe what they are for.

[godexsoft]

Adding a few more comments and questions 👍 I think we are very close to merging this 🥳

[godexsoft]

Looks good 👍🙏🚀

[godexsoft]

LGTM 🚀