Bugfix in TRAILLING_COMMA rule: insert comma in a proper place when there are exists comments

[kgevorkyan]

What's done:

• Bugfix in TRAILLING_COMMA: insert comma in a proper place when there are exists comments
• Expand tests

[codecov]

Codecov Report

Merging #1110 (a5a74df) into master (b188eab) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master    #1110      +/-   ##
============================================
+ Coverage     83.43%   83.44%   +0.01%     
  Complexity     2462     2462              
============================================
  Files           102      102              
  Lines          6146     6150       +4     
  Branches       1840     1842       +2     
============================================
+ Hits           5128     5132       +4     
  Misses          274      274              
  Partials        744      744              

Flag	Coverage Δ
unittests	83.44% <100.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...diktat/ruleset/rules/chapter3/TrailingCommaRule.kt	93.87% <100.00%> (+0.54%)	⬆️

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