Amp-wp: CLI integration shows internal methods as commands

[schlessera]

When I did work on refactoring the CLI commands, one of the initial steps was to make all internal methods private, so that the commands could act as command classes on their own.

Later, I noticed that the tests were built in such a way to require all internals to be public. So instead of rewriting all the tests, I opened another issue to introduce an abstraction layer (#3077) to remed this problem and come back to later. To make the tests pass for the build, I made the internals public again.

However, now, because of the changed command structure, all of the internal methods are exposed as subcommands because of this:

[schlessera]

This should be solved before the next release OR #3079 should not be included in that release.

[kienstra]

Thanks, I'll plan on code reviewing #3229 right away, and moving it to 'Ready For Merging' if/when it passes.