Feature: "private repo" persona

[woodruffw]

Pre-submission checks

• I am not reporting a bug (crash, false positive/negative, etc). These must be filed via the bug report template.
• I have looked through the open issues for a duplicate request.

What's the problem this feature will solve?

This is another valuable persona: there are developers who have 100% private repos where all maintainers are trusted, which means that a lot of "public untrusted input" vulnerabilities are less serious/not relevant.

We could do this with --persona=private or similar.

Describe the solution you'd like

Add a new "private repo" persona that's even less sensitive than the "regular" persona.

Additional context

h/t @MikeMcQuaid for the valuable idea 🙂

[woodruffw]

Leaving a note for myself: it probably makes sense to rename this --persona=trusted or similar, since it's about private repos or fully trusted contributors.