[META] Convert CivicTheme to use Single Directory Components (SDC)

Switching this to a planning issue.

Still need to finish the SDC conversion guide so moving to postponed for now.

We've been moving forward with this the last few days and sorting out the details. See the child issues.

Update summary with other issues.

kristen pol → credited alan.cole → .

kristen pol → credited febdao → .

kristen pol → credited jacobadeutsch → .

All child issues are done or moved so closing.

Note that all these components still exist in SDDS but have been prefixed with "old-" as they are not part of the demo anymore.

kristen pol → credited anand.toshniwal93 → .

Create Anand for work.