Update `redundantClosure` rule to preserve closure where if/switch expression would not be allowed

[calda]

This PR updates the redundantClosure rule to preserve closures with if/switch expressions if the closure is in a position where an if/switch expression would not be allowed. In Swift 5.9 if/switch expressions are only allowed as either return values, or as the result of an assignment.

This PR also fixes miscellaneous issues where redundantClosure didn't properly handle some combinations of explicit return, try/await, and if/switch expressions.

Fixes #1547 and #1548.

[codecov[bot]]

Codecov Report

Merging #1553 (3f34cf8) into develop (e3ec9af) will increase coverage by 0.02%. The diff coverage is 97.80%.

@@             Coverage Diff             @@
##           develop    #1553      +/-   ##
===========================================
+ Coverage    94.96%   94.98%   +0.02%     
===========================================
  Files           20       20              
  Lines        21670    21738      +68     
===========================================
+ Hits         20578    20648      +70     
+ Misses        1092     1090       -2     

Files	Coverage Δ
Sources/ParsingHelpers.swift	96.60% <100.00%> (-0.01%)	:arrow_down:
Sources/FormattingHelpers.swift	97.68% <97.22%> (+0.01%)	:arrow_up:
Sources/Rules.swift	98.53% <98.14%> (-0.01%)	:arrow_down:

... and 1 file with indirect coverage changes

[nicklockwood]

Thanks so much Cal ❤️

[calda]

Happy to heelllppp