Standardize formatting for the Perl code

[PEZ]

It is boring with PR feedback about formatting. 😄

We can standardize it with config that contributors can use to get the code formatted as we want. And consider making a check for it in CI. So that it is CI that brings the boring feedback. 😄

This seems to be pretty common to use: https://metacpan.org/pod/Perl::Tidy