R1:39f2bbaeea1b

Add Conduit Tokens to make authentication in Conduit somewhat more sane

Summary:
Ref T5955. Summary of intended changes:

**Improve Granularity of Authorization**: Currently, users have one Conduit Certificate. This isn't very flexible, and means that you can't ever generate an API token with limited permissions or IP block controls (see T6706). This moves toward a world where you can generate multiple tokens, revoke them individually, and assign disparate privileges to them.

**Standardize Token…