Retidy maint stuff
critic/docs for AST.pm
AST.pm: Normalise various spelling concerns
AST.pm: use `goto &sub` form
perlcritic.rc: add canonicalized as a stopword
Node.pm: Return explicitly from all subs
State.pm: Fix misc critic concerns
Node/Dependency.pm: Make code more obvious following critic notes
Node/Group/Use.pm: Apply critic
Node/TopLevel.pm: Apply critic
Node.pm: Add method documentation coverage
Node/Dependency.pm: Give documentation coverage
AST/State.pm: Improve documentation coverage
Node/Group/Use.pm: Documentation coverage
Node/Group/NotUse.pm: Add Abstract
Node/Group/And.pm: Add Abstract
Node/Group/Or.pm: Add Abstract
Node/TopLevel.pm: Add Abstract
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