refactor: reimplement the supervisor strategy

[Tochemey]

The new implementation simplifies a lot the Supervision strategy and now we can support the following strategies:

• OneForOne:
• OneForAll

along side a clean Directives enum:

• StopDirective
• ResumeDirective
• RestartDirective

[codecov]

Codecov Report

Attention: Patch coverage is 93.15068% with 20 lines in your changes missing coverage. Please review.

Project coverage is 83.58%. Comparing base (056ddcd) to head (35b7b8a).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
actor/pid.go	88.42%	10 Missing and 1 partial ⚠️
actor/pid_tree.go	92.10%	4 Missing and 2 partials ⚠️
actor/supervisor.go	95.52%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #625      +/-   ##
==========================================
+ Coverage   83.42%   83.58%   +0.15%     
==========================================
  Files         106      105       -1     
  Lines        9088     9160      +72     
==========================================
+ Hits         7582     7656      +74     
+ Misses       1160     1157       -3     
- Partials      346      347       +1     

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