Disable ProjectFile checkbox when it is a package file

[dotNomad]

This PR disables the checkbox for R and Python package files in the Project Files view, as well as includes a new tooltip when this is the case. It works very similar to #2487

Intent

Part of #1503

Type of Change

• • Bug Fix
• • New Feature
• • Breaking Change
• • Documentation
• • Refactor
• • Tooling

User Impact

Users can no longer un-check package files' checkboxes in the Project Files view - they can still check them to include the file if they are not included.

Automated Tests

New automated tests are included for the new tooltip.

Directions for Reviewers

Ensure that the R and Python package files, no matter the details in the configuration, can be unchecked.

Checking the checkbox for the file should still be available if the configuration is manually edited and the package file needs to be added.

[sagerb]

LGTM. I verified the functionality.

There was some strangeness when I opened some older deployments with configurations where the package file was not included. I had one circumstance in which the tree had the file not checked but disabled, however the file list included the renv.lock file. I think this may have been a refresh issue, and once I reloaded the window, everything worked fine. I did not have this issue on any other deployments or configurations that I checked.

Outside of that one occurrance, I was able to check the package file when it was not included in the files list, and it was added. I was then unable to remove it as designed by the disabled click.

Looks good to merge!