Monitor task: add timeout for monitor task, and support killing

[superstar54]

Add timeout input for monitor task.

Support killing the monitor task manually:

• Add kill action to the WorkGraph engine.
• Add workgraph task kill command.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 91.39785% with 8 lines in your changes missing coverage. Please review.

Project coverage is 79.99%. Comparing base (5937b88) to head (8b06867).
Report is 40 commits behind head on main.

Files	Patch %	Lines
aiida_workgraph/utils/control.py	71.42%	4 Missing ⚠️
aiida_workgraph/engine/workgraph.py	93.54%	2 Missing ⚠️
aiida_workgraph/workgraph.py	71.42%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #247      +/-   ##
==========================================
+ Coverage   75.75%   79.99%   +4.24%     
==========================================
  Files          70       65       -5     
  Lines        4615     4864     +249     
==========================================
+ Hits         3496     3891     +395     
+ Misses       1119      973     -146     

Flag	Coverage Δ
python-3.11	79.91% <91.39%> (+4.24%)	⬆️
python-3.12	79.91% <91.39%> (?)
python-3.9	79.95% <91.39%> (+4.21%)	⬆️

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