R1:5ee4a1a306c5

Give Harbormaster Build Plans real policies

Summary:
Ref T9614. Currently, a lot of Build Plan behavior is covered by a global "can manage" policy.

One install in particular is experiencing difficulty with warring factions within engineering aborting one another's builds.

As a first step to remedy this, and also generally make Harbormaster more flexible and bring it in line with other applications in terms of policy power:

- Give Build Plans normal view/edit policies.
- Require "Can Edit" to run a…