Define criteria for full 1.x Open Outreach release

Outstanding issues:

• #1331118: Ensure only stable releases are used for all major dependencies
• #1166474: Features in overridden state on install
• #1372126: Assess and address performance issues in Open Outreach
• #1457242: Open outreach fails when installing in a language other than English

Proposed changes that might be good to complete before a first full release:

• #1048984: Make UI components like contexts and menu items optional
• #1331150: Decide Open Outreach page layout approach for e.g. home page and section pages
• #1372086: Add new base theme to Open Outreach

Candidate features that could be included in a first full release:

• #1331470: Candidate Debut feature: Debut Highlighted, providing a highlighted content type and slideshow