Change the "intelligent" stage/group label inference logic to do the team -> stage/group inference first, and add a new "team to stage/group" inference logic

To be merged after !203 (merged) is merged and the first pass of 1:1 team -> stage/group inference is done for open issues.

Change the "intelligent" stage/group label inference logic to:

1. Do the team -> stage/group inference first.
2. Do the category/feature inference second.
3. Add a new "team to stage/group only" inference logic for merge requests that only do the team -> stage/group inference.
4. Consolidate the inference into a single policy file for both opened issues and MRs.

Closes #221 (closed), #235 (closed).