feat(restapi): support validate rule

[Rui-Gan]

Closes #2120

[codecov]

Codecov Report

Patch coverage: 77.27% and project coverage change: +0.06% 🎉

Comparison is base (3a72679) 61.65% compared to head (4b085b3) 61.70%.
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2153      +/-   ##
==========================================
+ Coverage   61.65%   61.70%   +0.06%     
==========================================
  Files         282      285       +3     
  Lines       33475    33583     +108     
==========================================
+ Hits        20636    20722      +86     
- Misses      10886    10904      +18     
- Partials     1953     1957       +4     

Files Changed	Coverage Δ
internal/server/rest.go	49.28% <66.67%> (+0.27%)	⬆️
internal/server/rule_manager.go	58.99% <100.00%> (+1.37%)	⬆️

... and 10 files with indirect coverage changes

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