feat(reader.go): reader支持配置的key本身含有点的情况

[yzrzr]

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

当配置文件中的key本身含有.分隔符时，无法正常获取配置，如：

users:
  james.smith:
    country: American
    age: 69

如上配置，目前使用users.james.smith还是users.james.smith.country都无法获取配置内容

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

fixes/resolves ##2382

Other special notes for the reviewers:

[codecov-commenter]

Codecov Report

Merging #2394 (3b9fbc4) into main (9737a3c) will decrease coverage by 0.07%. The diff coverage is 82.60%.

@@            Coverage Diff             @@
##             main    #2394      +/-   ##
==========================================
- Coverage   85.44%   85.37%   -0.08%     
==========================================
  Files          88       88              
  Lines        3780     3808      +28     
==========================================
+ Hits         3230     3251      +21     
- Misses        383      389       +6     
- Partials      167      168       +1     

Impacted Files	Coverage Δ
config/reader.go	79.36% <82.60%> (-1.25%)	:arrow_down:

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