[runsascoded/ghpr#6] Improve help text, refactor command registration, and fix test assertions
This PR includes three improvements to the ghpr codebase:
- Draft flag validation - Added error when using
-dwithout-y, since draft mode is incompatible with web editor - Clearer help text - Updated
createcommand and flag descriptions to clearly explain the three modes:- Default (no
-y): Interactive web editor (waits for user) -yonce: Create via API then view result
- Default (no