Improve scan --github-org=ORG UX

[bradlarsen]

No description provided.

[bradlarsen]

I need to think about the behavior of this a bit more. Consistent path handling in a way that's portable across environments is a bit tricky.

[bradlarsen]

My thoughts on path handling:

Paths that are recorded to the datastore by Nosey Parker should ideally not be locked to the particular machine that performed the scanning.

The motivating use case: someone scans on one machine, and then is able to meaningfully review the findings on another machine, without having to manually translate paths. (This scenario happens more commonly when scanning is done using the Docker container, and then review / triage is done outside the container.)

To avoid tying the paths recorded in the datastore to the scanning machine, this means:

1. Absolute paths that reference the inputs files should be avoided. If the user specifies relative paths on the command line, those should be used for recording in the datastore, rather than canonicalizing them. (This PR fixes one place where absolute paths were being used — scan --github-org=ORG.)

2. (Unsure) Relative paths for inputs should be made relative to the datastore used for scanning?

Anyway, this can be revisited. For now, I'll merge these fixes.