Categorize various flavors of if in Ruby as if nodes

[noahd1]

In https://github.com/orgs/qltysh/discussions/1313 @nk-ty noted that qlty and codeclimate CLIs calculate the cognitive complexity of a method with trailing unless statements differently. After some investigation, I determined that both were incorrectly calculating cognitive complexity. This PR is concerned with the cognitive complexity calculation in qlty.

The following are equivalent ways of expressing an if conditional in Ruby:

if !foo
    puts "hi"
end

unless foo
    puts "foo"
end

puts "hi" if !foo

puts "hi" unless foo

The first was correctly being calculated. The second was an obvious oversight. And the 3rd and 4th ones were less obvious oversights (the parser calls them if_modifier / unless_modifier nodes not if / unless nodes.

This PR categorizes all 4 as if_nodes which the cognitive complexity calculator uses, and correctly penalizes all 4 as 1 point.

[qltysh]

The code coverage on the diff in this pull request is 100.0%

Drilldown

Path	File Coverage Δ
qlty-config/src/library.rs	-0.7
qlty-smells/src/metrics/metrics/cognitive.rs	0.0
qlty-analysis/src/lang/ruby.rs	0.0

[brynary]

Nicely done!