feat(config): config support custom merge config

[shenqidebaozi]

Description (what this PR does / why we need it):

Which issue(s) this PR fixes (resolves / be part of):

Other special notes for the reviewers:

[codecov-commenter]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (d13071e) 84.28% compared to head (729f48b) 84.37%.

❗ Current head 729f48b differs from pull request most recent head 0d11490. Consider uploading reports for the commit 0d11490 to get more accurate results

Files	Patch %	Lines
config/config.go	0.00%	2 Missing and 1 partial ⚠️
config/reader.go	0.00%	0 Missing and 1 partial ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3106      +/-   ##
==========================================
+ Coverage   84.28%   84.37%   +0.09%     
==========================================
  Files          88       88              
  Lines        3984     3988       +4     
==========================================
+ Hits         3358     3365       +7     
+ Misses        449      447       -2     
+ Partials      177      176       -1     

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