Bugfix for boolean expressions

[petertrr]

What's done:

• Fixed logic in boolean expression formatter
• Added tests
• Enabled de Morgan's law for boolean expression simplification
• Fixed code style

Which rule and warnings did you add?

This pull request closes #908

TODO:

• Support xor

[codecov]

Codecov Report

Merging #909 (9e29d65) into master (0218da1) will decrease coverage by 0.01%.
The diff coverage is 89.13%.

@@             Coverage Diff              @@
##             master     #909      +/-   ##
============================================
- Coverage     84.19%   84.18%   -0.02%     
- Complexity     2357     2373      +16     
============================================
  Files           101      101              
  Lines          5981     6002      +21     
  Branches       1762     1772      +10     
============================================
+ Hits           5036     5053      +17     
- Misses          257      260       +3     
- Partials        688      689       +1     

Flag	Coverage Δ
unittests	84.18% <89.13%> (-0.02%)	⬇️

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

Impacted Files	Coverage Δ
...diktat/ruleset/rules/chapter2/kdoc/KdocComments.kt	85.18% <50.00%> (ø)
.../diktat/ruleset/rules/chapter1/IdentifierNaming.kt	83.73% <60.00%> (-0.42%)	⬇️
...iktat/ruleset/rules/chapter3/files/NewlinesRule.kt	78.35% <66.66%> (ø)
...t/ruleset/rules/chapter3/BooleanExpressionsRule.kt	92.92% <96.87%> (-2.14%)	⬇️
...les/chapter4/VariableGenericTypeDeclarationRule.kt	79.31% <100.00%> (ø)
...diktat/ruleset/rules/chapter6/AvoidUtilityClass.kt	77.27% <100.00%> (ø)
.../cqfn/diktat/ruleset/rules/chapter6/RunInScript.kt	92.30% <100.00%> (ø)
...tlin/org/cqfn/diktat/ruleset/utils/AstConstants.kt	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 0218da1...9e29d65. Read the comment docs.