apis: add Mid tier api

[saintube]

Ⅰ. Describe what this PR does

Add apis for node recommendation and Mid tier.

Proposed in #1385.

Ⅱ. Does this pull request fix one issue?

Part of #1361.

Ⅲ. Describe how to verify it

Ⅳ. Special notes for reviews

V. Checklist

• I have written necessary docs and comments
• I have added necessary unit tests and integration tests
• All checks passed in make test

[saintube]

/cc @hormes @zwzhang0107 @eahydra

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.02 ⚠️

Comparison is base (341fdd8) 64.77% compared to head (9c9a87b) 64.75%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1375      +/-   ##
==========================================
- Coverage   64.77%   64.75%   -0.02%     
==========================================
  Files         334      333       -1     
  Lines       34311    34296      -15     
==========================================
- Hits        22226    22210      -16     
+ Misses      10457    10455       -2     
- Partials     1628     1631       +3     

Flag	Coverage Δ
unittests	64.75% <ø> (-0.02%)	⬇️

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see 28 files with indirect coverage changes

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[jasonliu747]

will there be a proposal for recommendation feature?

[saintube]

will there be a proposal for recommendation feature?

Yes. The proposal will be submitted in another PR.

[saintube]

/hold

[saintube]

/unhold

[hormes]

/lgtm
/approve

[koordinator-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hormes

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• apis/OWNERS [hormes]
• config/OWNERS [hormes]

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