Refactoring OverviewCommandHelper (2/3)

This CL should not affect the behavior of OverviewCommandHelper.
- It splits executeCommand into smaller functions
- Rearrange public/private functions
- Adds extra logs.

Bug: 352046797
Bug: 351122926
Flag: EXEMPT bugfix.
Test: Manual.
Change-Id: I283f179794af812973a559db6291febe19e3c6d7