Disable project related functionality if PROJECTS_ENABLED=False

[theskumar]

• do not register project urls
• do not register project menu in wagtail
• do not enable contracting/finance dashboard

Fixes #3606

Project settings and vendor settings will still be present, I could not find a way to hide/disable them conditionally.

Test Steps

• [ ] Set PROJECTS_ENABLED=False
• [ ] check dashboard, wagtail admin and finance roles
• [ ] general site-wide checks
• [ ] try visit the urls related to project/finance directly

[wes-otf]

slick! works well.