feat(build-cli): Add handler exclusion and listing to check policy command

[tylerbutler]

Adds an --excludeHandler flag to the check policy command that can be used to exclude one or more handlers by name. The main use-case for this is to run policy check with or without the assert-shortcodes handler more easily. Technically it's possible to exclude a single handler using the regex argument, but this is much simpler.

Also, there is a new --listHandlers flag that will list all the handlers including their names, so one can now query the system for handlers, then exclude those handlers by name easily.