Add ability to run on workflow_dispatch

[sc0ttkclark]

Having PR runs is great but I'd love to run on a workflow_dispatch so that I could have it looking at the whole codebase. This wouldn't add comments inline but at least it could give me a pass/fail status on the action run as well as further detail in the action log for what failed.

### Tasks
- [ ] Add logic to use current git ref instead of looking at PR event info, if PR event not available
- [ ] If not looking at a PR event, bypass PR comments/review logic