Check for boolean in while conditions

[VincentLanglet]

Might be enough to close #259

I tried to implement the same thing for For_.

But the issue I encounter in

for ($i = 0; $i; $i++) {}

is that $i is considered as a MixedType, which is non explicit, so BooleanHelper::passesAsBoolean always return true.

So i'm unsure the rule is doable for for loops.

[VincentLanglet]

Friendly ping @ondrejmirtes if you find some time 👍

[ondrejmirtes]

This is a new rule. It has to be part of bleeding edge. See how this was done in 1.x:

phpstan-strict-rules/rules.neon

Line 20 in b564ca4

disallowedLooseComparison: [%strictRules.allRules%, %featureToggles.bleedingEdge%]

This also means this needs a new config parameter. Something like booleansInLoopConditions?

[VincentLanglet]

Sure, should be ok now