Implement foundational flows enablement with namespace service account

Problem

There are dependencies on other work in #568031 (closed) that is not yet completed for making the AI catalog the leading component for foundational flows. With limited time remaining before the deadline, we need a clearer path forward that follows existing patterns with less dependency risks.

To make AI catalog the leading component would require:

1. Actually able to create Flows in AI catalog and add them to a project
2. Sync foundational flows to DWS from AI catalog
3. Automatically create service account when creating a Flow (does this work already?)
4. Determine a connection between the buttons and a Flow, essentially allow button as a trigger for flow

Deliverables

1. Create an "Allow foundational flows" setting that controls the visibility of the buttons that trigger foundational flows
2. Update FE to render the buttons conditionally on the above setting
3. Create a namespace SA for .com that is used by the flows for composite identity
4. Remove composite identity screen

This approach follows existing patterns and has clearer defined scope with less dependency risks.