Removing effect-less pragmas

perl version bundles and various CPAN modules would turn on `strict` / `warnings`, which means the traditional `use strict`, `use warnings` becomes no-ops and should be removed.

Furthermore, some forms of `use feature` could be removed when a, say,`use v5.36` is nearby.

Start by locating the pragma analysis and rewrite entry points in the repository, then inspect how Perl versions and nearby declarations are represented. Define the cases where strict, warnings, or feature pragmas are redundant, and add coverage showing that only effect-less pragmas are removed without changing program behavior.

Written by the indexing model from the issue text.