Uniformize compare-to-zero, compare-to-empty-string with the use-implicit-booleaness-x checks

[Pierre-Sassoulas]

Current problem

compare-to-zero and compare-to-empty-string are the same check basically than use-implicit-booleaness-not-copmparison.

Doing x != 0 feel safer and easier to understand than bool(x) for int (you need a background in C to understand that). Socompare-to-zero feel more opinionated which is probably why they are in their own optional checker.

compare-to-empty-string though is really an use-implicit-booleaness-not-copmparison check.

Desired solution

I think it would make sense to merge compare-to-empty-string . Renaming them so they all follow the same pattern could be an option.

Additional context

#6861

I've done the work in #6870 then realized that compare-to-zero was opinionated.

[DanielNoord]

I think the compare-to-zero should stay an extension. Implicit booleanness of string does make sense to merge.