Add support for querying users by email

[liuyiwuqing]

What type of PR is this?

/kind improvement

What this PR does / why we need it:

Add spec.email query for user endpoint.

Which issue(s) this PR fixes:

Fixes #7432

Does this PR introduce a user-facing change?

用户搜索支持根据邮箱地址

[CLAassistant]

All committers have signed the CLA.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[JohnNiang]

Thank you for your first contribution!

Please sign CLA first before getting merged. You can rerfer to #7441 (comment).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.44%. Comparing base (04c27db) to head (b4a00f4).
Report is 13 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #7441   +/-   ##
=========================================
  Coverage     59.44%   59.44%           
  Complexity     4142     4142           
=========================================
  Files           701      701           
  Lines         24014    24015    +1     
  Branches       1543     1543           
=========================================
+ Hits          14274    14275    +1     
  Misses         9078     9078           
  Partials        662      662           

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[ruibaby]

/lgtm

[JohnNiang]

/approve