Fix issues with _get_list_table()

[IanDelMar]

This PR fixes the return types of _get_list_table() and resolves the "not always the same as T. It breaks the contract for some argument types, typically subtypes" issue (see at phpstan.org/try). The PHPStan version is updated to 1.11 to support new<T>.

Compared to the current implementation, we lose the check for whether $class_name is a class-string. Once we drop support for PHPStan 1.x, we can update '@phpstan-template T' => 'of string' to '@phpstan-template T' => 'of class-string' to restore the check that $class_name is a class-string. I don't think that new<T> is supported by Psalm.

Once merged, #256 can be closed.

Fixes #257
Related to #256

Another option to resolve this is to revert migrating the dynamic return type extension from szepeviktor/phpstan-wordpress.

cc: @johnbillion

[szepeviktor]

This is a great PR.

Waiting for John ... and @swissspidy

[IanDelMar]

Perhaps @kkmuffme would also like to have a look regarding the Psalm support. Any feedback would be greatly appreciated.

[johnbillion]

I don't have time to look deeply into this at the moment. I trust Ian's judgement.

[szepeviktor]

We have just taken off without landing gears.

[kkmuffme]

So basically this PR is only needed bc phpstan 1 does not support class-string in template and would be reverted later? Not sure if that change is a good idea to begin with then.

[szepeviktor]

Anyone able to answer?

[IanDelMar]

So basically this PR is only needed bc phpstan 1 does not support class-string in template and would be reverted later? Not sure if that change is a good idea to begin with then.

This PR was necessary because we were encountering incorrect return types. Unfortunately, I was unable to resolve the issues with _get_list_table() by any other means. Admittedly, I am not an expert, and the only alternative I could think of was to remove it entirely and revert to providing the return types via the return type extension in szepeviktor/phpstan-wordpress. I am, however, open to alternative suggestions and happy to consider any advice you might have.