Fixed the issue with knife -h command showing invalid subcommands

[ashiqueps]

Description

The knife -h command was showing invalid subcommands such as COMMAND COMMAND, SERVER COMMAND, RESOURCE COMMAND, etc., which were coming from the subclasses.

This PR updates the code to skip classes defined inside a subdirectory of the lib/chef/knife/ tree (e.g. lib/chef/knife/cloud/server/create_command.rb). By convention, real knife subcommands live directly at lib/chef/knife/.rb — the same flat pattern that GemGlobLoader uses when discovering commands. Abstract base classes from plugins like knife-cloud are nested in subdirs and are only loaded transitively; registering them causes spurious categories (e.g. ** SERVER COMMANDS **) to appear in 'knife --help'.

Related Issue

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (non-breaking change that does not add functionality or fix an issue)

Checklist:

• I have read the CONTRIBUTING document.
• I have run the pre-merge tests locally and they pass.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• If Gemfile.lock has changed, I have used --conservative to do it and included the full output in the Description above.
• All new and existing tests passed.
• All commits have been signed-off for the Developer Certificate of Origin.

[tpowell-progress]

Any tests or validation of this? I don't see example output from testing or anything.

[ashiqueps]

@tpowell-progress Added tests, please review.