style: Enforce perlcritic rule ProhibitImplicitNewlines

[perlpunk]

ValuesAndExpressions::ProhibitImplicitNewlines

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏

[perlpunk]

The problem with this rule is that it complains about signatures spanning multiple lines:

#   ::warning file=t/lib/OpenQA/Test/Utils.pm,line=553,col=14,title=Literal line breaks in a string - severity 3::[ValuesAndExpressions::ProhibitImplicitNewlines] See pages 60,61 of PBP
[23:16:41] xt/02-perlcritic.t ........ 

sub test_cmd (
    $cmd, $args,
    $expected = qr//,
    $test_msg = 'command line is correct',
    $exit_code = 0,
    $exit_code_msg = 'command exits successfully'
  )
{

The reasons are:

• This is by default read as a prototype, not a signature
• The class PPI::Token::Prototype inherits from PPI::Token::Quote::Literal surprisingly, so the perlcritic rule also considers those as quoted strings

There is an issue about it:

• Subroutine signatures recognized as prototypes Perl-Critic/Perl-Critic#591
  It contains a suggested fix to enable recognizing subroutine signatures:
  Subroutine signatures recognized as prototypes Perl-Critic/Perl-Critic#591 (comment)

PPI_CUSTOM_FEATURE_INCLUDES='Mojo::Base: {signatures: perl}' perlcritic t/lib/OpenQA/Test/Utils.pm

With this it passes, but maybe this is not important enough for now.
It would also automatically pass when we switch to use v5.40 at some point.

So I would mark this as not-ready for now, and we can exclude the policy.