Popping from stash (with merge conflict) causes issues

[isc-etamarch]

Based on customer feedback

If popping changes from stash results in a merge conflict, the GitUI errors out, and the production is left in a broken state (in merge conflict state). There is no way to fix this through the UI, only manually fixing the merge conflict in the code.

We need to allow for a way to resolve the merge conflict without going directly into the code.

@isc-tleavitt What are your thoughts?

[isc-tleavitt]

I think the right option would be:
Attempt production configuration auto-resolve
If that fails, cancel the stash pop/apply (ideally preserving the stash?)

This is also a pointer toward recommending basic mode / per-developer namespaces to the customer, if not production decomposition when available, either of which would have provided a route less likely to encounter this issue.

[isc-etamarch]

This also causes the workspace view to error out. Trying to commit this change does not work, though discarding this file does not actually discard the file

[isc-tleavitt]

The other resolution option is to use the Web Application view of the repository, which gives you isfs access to the raw files. But we can't have that as the only/default option, and there needs to be a path to sanity through the UI.