IgnoredReturnValue: Fix false positive on chained statements

[cortinico]

Update the IgnoredReturnValue to use getTopmostParentOfType instead of getParentOfType. This allows use to capture the whole chain statement and not just the direct parent.

Moreover, I'm adding a check to make sure that chains that consumes a value (i.e. returns a Unit) are excluded from the inspection.

Fixes #2890

[codecov]

Codecov Report

Merging #2895 into master will decrease coverage by 0.01%.
The diff coverage is 60.00%.

@@             Coverage Diff              @@
##             master    #2895      +/-   ##
============================================
- Coverage     80.18%   80.17%   -0.02%     
- Complexity     2425     2426       +1     
============================================
  Files           421      421              
  Lines          7369     7373       +4     
  Branches       1349     1351       +2     
============================================
+ Hits           5909     5911       +2     
  Misses          761      761              
- Partials        699      701       +2     

Impacted Files	Coverage Δ	Complexity Δ
...arturbosch/detekt/rules/bugs/IgnoredReturnValue.kt	79.16% <60.00%> (-2.66%)	12.00 <0.00> (+1.00)	⬇️

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