Revert non-empty-string changes and add regression test

[herndlm]

Closes #85
Includes #88
Reverts 19b869e and 9009135

Adapts the ImpossibleCheckTypeMethodCallRuleTest to use phpstan-strict-rules so that checkAlwaysTrueCheckTypeFunctionCall is enabled and we can actually regression test #85

Sorry all for all the troubles caused :/

[ondrejmirtes]

Perfect, gonna release it right away. We can then talk about the solution :) Thank you.

[herndlm]

Thx Ondrej for the quick review, merge and release!

Let me know if you have any ideas already how to move forward with the type problems and ImpossibleCheckTypeMethodCallRule. In the context of this extension this seems to be making problems sometimes, e.g. #68 too for example (with the modified rule test here this can be reproduced now too).

In general I guess this starts to get problematic if the assertions do more than simple type checks (e.g. assertCount, assertLength or assertUuid). But I have no idea how to solve that right now unfortunately. It all comes down to phpstan's core ImpossibleCheckTypeHelper that finds the specified types and the rule that then finds out that no more information type-wise (non-empty-string is still going to be a non-empty-string after checking that it is a valid UUID for example) is added.