Add event broadcasting capability

[ankona]

Event broadcasting will enable the system to notify other MLI resources of changes. This PR contains the base capabilities required for publishing & consuming channel messages as events.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 232 lines in your changes missing coverage. Please review.

Please upload report for BASE (mli-feature@f6d55d8). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...i/infrastructure/storage/backbone_feature_store.py	0.00%	172 Missing ⚠️
.../_core/mli/infrastructure/storage/feature_store.py	0.00%	42 Missing ⚠️
...mli/infrastructure/storage/dragon_feature_store.py	0.00%	9 Missing ⚠️
...e/mli/infrastructure/control/request_dispatcher.py	0.00%	5 Missing ⚠️
smartsim/_core/utils/timings.py	0.00%	4 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff               @@
##             mli-feature     #672   +/-   ##
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  Coverage               ?   69.65%           
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  Files                  ?      103           
  Lines                  ?     8732           
  Branches               ?        0           
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  Hits                   ?     6082           
  Misses                 ?     2650           
  Partials               ?        0           

Files with missing lines	Coverage Δ
smartsim/_core/utils/timings.py	0.00% <0.00%> (ø)
...e/mli/infrastructure/control/request_dispatcher.py	0.00% <0.00%> (ø)
...mli/infrastructure/storage/dragon_feature_store.py	0.00% <0.00%> (ø)
.../_core/mli/infrastructure/storage/feature_store.py	0.00% <0.00%> (ø)
...i/infrastructure/storage/backbone_feature_store.py	0.00% <0.00%> (ø)

[mellis13]

Just some comments before seeing the integration additions.

[al-rigazzi]

Just one thing that I'd like to be addressed, namely the different timeouts. The rest looks very promising!

[AlyssaCote]

A few more tiny comments :)

[AlyssaCote]

Just a couple more comments :)

[al-rigazzi]

LGTM!