Add draft rfc for livestate feature in plugin architecture

[ffjlabo]

What this PR does:

as title

Why we need it:

Which issue(s) this PR fixes:

Part of #5363

Does this PR introduce a user-facing change?:

• How are users affected by this change:
• Is this breaking change:
• How to migrate (if breaking change):

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 25.44%. Comparing base (b8070a9) to head (a5bf076).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5364   +/-   ##
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  Coverage   25.44%   25.44%           
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  Files         446      446           
  Lines       47844    47844           
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  Hits        12172    12172           
  Misses      34720    34720           
  Partials      952      952           

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🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[t-kikuc]

Great flow chart!

It seems complex to handle some points which are specific to some plugins.
e.g. pass it to the executor.Input and use it on the k8s stage

[Warashi]

LGTM

[ffjlabo]

It seems complex to handle some points which are specific to some plugins.
e.g. pass it to the executor.Input and use it on the k8s stage

That's true. In my understanding, livestatestore is used only in the executor.
So I plan to use livestatestore directly from the executor in the plugin side.