Support more formats of input for repo url

[dmwyatt]

Description:

Enhance the flexibility of the GitHub repository URL input field on our form.

Objective:

Update the repository URL form field to handle the following input variations and normalize inputs:

1. Domain included: github.com/user/repo
2. Short form: user/repo
3. Full URL: https://github.com/user/repo
4. queries or fragments: https://github.com/user/repo?query=string#fragment. Remove them.

Tasks:

1. Review Current Implementation: RepositoryURLForm is where most of the work should happen.

2. Update Validation Logic: Ensure the validate_repo_url function can accurately validate the supported input formats.

3. Enhance Cleaning Logic: Modify the clean_repo_url method to:

   • Normalize input to a standard format, prepending https://github.com/ where necessary.
   • Remove any query parameters or fragments from the URL.

4. Implement and update Test Cases: Create/update tests to confirm:

   • Acceptance and correct normalization of all supported formats.
   • Effective stripping of query parameters and fragments.
   • Proper functioning of both client and server-side validation mechanisms.

5. Documentation Update: Revise documentation to clearly explain the input formats supported and the behavior regarding extraneous URL components.