v2 Implement LazyCommand for deferring modules until their commands are invoked, and make PrefixTrie public

v2 Implement LazyCommand for deferring modules until their commands are invoked, and make PrefixTrie public: a task in aws-cli-diff (Harbor dataset). Title: v2 Implement LazyCommand for deferring modules until their commands are invoked, and make PrefixTrie public