enhance(advisor): power cap service supports GetAdvice

[h-w-chen]

What type of PR is this?

Enhancements - power cap advisor supports GetAdvice unary GRPC protocol, with long polling ability

What this PR does / why we need it:

This PR implements GetAdvice method of new advisor-qrm communication protocol. To avoid communication overhead, it leverages long-polling so as to reduce the client requests resulting empty responses.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 92.04545% with 7 lines in your changes missing coverage. Please review.

Project coverage is 60.91%. Comparing base (a0b161a) to head (9ae1338). Report is 59 commits behind head on main.

Files with missing lines	Patch %	Lines
...advisor/plugin/poweraware/capper/server/service.go	89.06%	7 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #832      +/-   ##
==========================================
+ Coverage   60.78%   60.91%   +0.13%     
==========================================
  Files         613      613              
  Lines       64787    64917     +130     
==========================================
+ Hits        39378    39546     +168     
+ Misses      21426    21384      -42     
- Partials     3983     3987       +4     

Flag	Coverage Δ
unittest	60.91% <92.04%> (+0.13%)	:arrow_up:

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