Provide example on predicate usage for shared streams

[Danil-Grigorev]

Motivation

Provide an example for event filtering, while leaving original watch stream unmodified. May be useful for sharding controller logic, where reconcile is only needed in case of a specific change.

Solution

Potentially looking for better suggestions to approach topic of comparing previous and current resource state.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.4%. Comparing base (7ff120a) to head (0eec3ab).
Report is 4 commits behind head on main.

Additional details and impacted files

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##            main   #1552   +/-   ##
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  Coverage   75.4%   75.4%           
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  Files         80      80           
  Lines       7290    7290           
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  Hits        5495    5495           
  Misses      1795    1795           

[clux]

Sorry for the slow response on this.

I was a bit unsure of what to do here because we are a bit sure of how the multiplexing for shared streams should actually interact with stream extensions (from WatchStreamExt) and we haven't really done that investigation properly yet. Happy to merge as is and resolve that at a later date though personally.