feat: Refactor backend to a rest api

[ix-56h]

Main topic

The current webapp doesn't provide API endpoints to communicate with the backend, instead, we got endpoints that returns fully generated HTML pages, then, the frontend replace the whole DOM with the new HTML.

This PR provide a REST api and fix the auto generated openapi.json and Swagger UI.

Changes

• /api old endpoints doesn't redirect to an deprecated docs
• /api/ingest new endpoint provides an easy way to ingest any repository with a simple POST request.
• new pydantic models for the ingest endpoint, both request body and responses.
• The new endpoint returns a JSON response and provides well defined JSON response object for each possible scenarios (OK, ERROR, INTERNAL ERROR, MALFORMED REQUEST)
• The new Swagger ui (and the generated openapi.json file used to render it) list only useful endpoints with comprehensive description (refer to the screen bellow)
  

Testing

The old test_integration_flow.py have been fixed to make it works with the new endpoint.

To test it manually, run the uvicorn server and see the /docs endpoint to perform requests.

Please test the usual workflow (the url trick and ingest form submission), it works for me but i don't have enough experience with the product.

[filipchristiansen]

I think you can make these changes

git_form.jinja

-              onsubmit="handleSubmit(event{% if is_index %}, true{% endif %})">
+              onsubmit="handleSubmit(event, true)">

git.jinja
-    {% with is_index=false, show_examples=false %}
+    {% with show_examples=false %}


index.jinja
-    {% with is_index=true, show_examples=true %}
+    {% with show_examples=true %}