Update document upload api to enhance existing document upload experience

[vishnoianil]

PR enhances the document upload APIs.

• All the contributions (knowledge and skill) now given the name
  on creation and not on submit from server side, to drive the
  workflow using the contribution name.
• User is allowed to see the document only related to that knowledge
  contribution, rather than all the documents across all the
  contributions.
• Documents are now submitted when user submits the contribution.
• Existing documents are fetched when user edits the contribution. Both
  newly uploaded documents and the existing documents are presented to
  the user.
• If user cancel the edit or doesn't submit the contribution, new documents
  are not uploaded and the existing commit sha will remain in the yaml.
• If user edits the knowledge contribution and adds more documents,
  all the existing and new documents will be shown to the user and
  submitted when user submit the contribution.
• User don't have to worry about the commit sha anymore. Api
  implementation takes care of collecting all the documents
  and committing them in a single commit, and using that in the yaml.
• API's also provide option to user to delete any of the existing
  uploaded document, but it's currently is not used. We need to
  design a workflow on how user can manage the contribution related documents.
• This workflow works similarly for both github and native mode.

Fixes #608

[vishnoianil]

Screen.Recording.2025-03-19.at.1.08.12.AM.mov

@Misjohns @jeff-phillips-18 This recording contains the demo of the new document upload workflow. PTAL

[Misjohns]

@vishnoianil The upload docs looks great. Thank you!
I have a few comments on the context selection modal. Should I capture those here or on another issue?

[vishnoianil]

@vishnoianil The upload docs looks great. Thank you!

I have a few comments on the context selection modal. Should I capture those here or on another issue?

Hi @Misjohns , please add it here, if they are minor changes, i can take care of it in this PR, otherwise i will open another issue.

[jeff-phillips-18]

@vishnoianil Tested and works well.

I'm wondering if, when editing, we should show the already uploaded documents on the Upload documents. This could give the user a) advance information on what docs are available for selecting context from, and b) the ability to remove previously uploaded documents. Thoughts?

[Misjohns]

@jeff-phillips-18 I agree. If a user chooses to edit a submission, then I'd expect to see the markdown files that were previously created in the submission.

[Misjohns]

@vishnoianil We already had an existing issue for improving the select context modal. #568

[vishnoianil]

@jeff-phillips-18 @Misjohns Agree on adding the existing files to the list. I was thinking of that as well, and I was also thinking of allowing users to delete the file from the list. For delete It will pop-up a warning with the text similar to "Please ensure that selected contexts does not belong to this document.".

@Misjohns Regarding #568 , let's take it through another PR. This PR is more focussed on the backend APIs, so want to make sure it works with the existing current flow.

[jeff-phillips-18]

Overall, LGTM. Works well.

[nerdalert]

LGTM!