infra: setup signal handling with SA_ONSTACK flag

[canepat]

This PR changes the implementation of SignalHandler to relying on sigaction system call on Linux and macOS platforms, so that we can use SA_ONSTACK flag on registered signal handlers.

Fixes #1940

[JacekGlen]

Tiny change only. Looks good!

[codecov]

Codecov Report

Attention: Patch coverage is 70.58824% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 53.34%. Comparing base (2eabf8a) to head (05aa102).
Report is 5 commits behind head on master.

Files	Patch %	Lines
silkworm/infra/concurrency/signal_handler.cpp	68.75%	2 Missing and 3 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1943   +/-   ##
=======================================
  Coverage   53.33%   53.34%           
=======================================
  Files         621      621           
  Lines       45881    45894   +13     
  Branches     7043     7044    +1     
=======================================
+ Hits        24470    24481   +11     
- Misses      19290    19295    +5     
+ Partials     2121     2118    -3     

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