Move export/init/embedding runs to be endpoints in retrieval service

[Yuan325]

Move the export / init / embedding runs to be endpoints in the service vs. standalone.

The init was done within terraform-genai-rag as a part of the JSS.

This will be helpful in setting up certain pipeline so user wouldn't have to run python run_database_init.py etc. Instead, they can just call the endpoint to set up init.

[mahimairaja]

What do you think or converting this entire scripting to a REST api using FastAPI?
@Yuan325