Require content templates to have at least one dynamic property source

Overview

Originally Content Templates were required have at least 1 dynamic prop source.

It was enforce by the schema

        ComponentTreeMeetRequirements:
          inputs:
            absence:
              - adapter
            # This tree MUST contain at least one dynamic prop source, or it's not much of a template;
            # it's just presenting static data.
            presence:
              - dynamic

but this meant that in many issues in 🌱 [META] Content templates Active were blocked by this requirement.
Because these were not done
📌 ComponentSourceInterface::inputToClientModel needs to support passing an entity Active
📌 Move `PropSourceEndpointTest` into new `XbConfigEntityHttpApiTest::testComponent()` Active

It also allowed
📌 Refactor ApiLayoutController into 2 sub-class to support Content Templates Active
✨ Render template and support component operations in preview canvas Active
which were the first 2 issue creating the UI to be completed without solving all the dynamic link problem

Proposed resolution

Add back enforcement and the test coverage that was removed in 📌 Refactor ApiLayoutController into 2 sub-class to support Content Templates Active
There was test MR that shows just the changes that need to reversed https://git.drupalcode.org/project/experience_builder/-/merge_requests/1438

User interface changes