Improve count() narrowing of constant arrays

[herndlm]

Generalizes the already existing solution (wow, this is way more complicated than I thought!) and uses it outside of union types as well. I kind of had to make the "isNormalCount" determination a bit more dry, which unfortunately made the diff worse..

I did do a performance comparison with hyperfine running make phpstan and didn't notice any changes, but my system is not the best.

Closes phpstan/phpstan#12190

I see that the issue bot spits out two more change than on my other PR which only touches tests, but I'm too lazy to compare which one it is :D

[herndlm]

I know, I changed that narrow* method to return Type instead of SpecifiesTypes. Maybe I'll change this back again tomorrow.

[herndlm]

I know, I changed that narrow* method to return Type instead of SpecifiesTypes. Maybe I'll change this back again tomorrow.

adapted. looks better now IMO. The master plan is to move more common things for both count() == xx and count > xx specification into the now renamed specifyTypesForCountFuncCall(). Would also be great if turnListIntoConstantArray() goes away completely or is only used internally once... But for here this is more than enough IMO.

@staabm what do you think about this?

[staabm]

what do you think about this?

this PR looks great, thanks for cleaning up after me :)

[herndlm]

Should stuff like this be based on 1.12.x or latest dev branch? I sometimes have issues deciding 😅