feat: support modify sqlSource field index value

[Yisaer]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 67.12329% with 24 lines in your changes are missing coverage. Please review.

Project coverage is 63.18%. Comparing base (c258a6a) to head (90d3032).

Files	Patch %	Lines
internal/server/rule_state.go	76.00%	12 Missing ⚠️
internal/topo/topo.go	0.00%	9 Missing ⚠️
internal/topo/node/source_node.go	33.33%	2 Missing ⚠️
internal/server/rest.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2730      +/-   ##
==========================================
+ Coverage   63.17%   63.18%   +0.02%     
==========================================
  Files         346      347       +1     
  Lines       39322    39395      +73     
==========================================
+ Hits        24838    24891      +53     
- Misses      12315    12336      +21     
+ Partials     2169     2168       -1     

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[ngjaying]

I prefer a general state read/write API, not specific to SQL index value.