Fixed BracesInConditionalsAndLoopsRule and added tests

[DrAlexD]

What's done:

• Reworked insertEmptyBlock() function for adding empty braces blocks to conditions and do-while loop with empty bodies.
• Added check for braces block existence to avoid duplicate braces block.
• Added tests for conditions including tests for cases of else if and cases of empty if and else bodies.

It's part of #1737

[codecov[bot]]

Codecov Report

Merging #1750 (3fdde5f) into master (17d4bcc) will increase coverage by 0.30%. The diff coverage is 73.33%.

@@             Coverage Diff              @@
##             master    #1750      +/-   ##
============================================
+ Coverage     76.10%   76.40%   +0.30%     
- Complexity     2283     2296      +13     
============================================
  Files           126      126              
  Lines          8243     8273      +30     
  Branches       2070     2081      +11     
============================================
+ Hits           6273     6321      +48     
+ Misses         1050     1027      -23     
- Partials        920      925       +5     

Files Changed	Coverage Δ
...rules/chapter3/BracesInConditionalsAndLoopsRule.kt	84.44% <73.33%> (+21.58%)	:arrow_up: