Profiler: Number each processor type separately from 0

[manopapad]

E.g. start from GPU 0 rather than GPU 4, which is confusing.

Currently the ID matches the Realm processor ID, to make cross-referencing with error messages etc. easier. We could instead list the Realm processor ID somewhere close to the "user friendly" processor ID.

[lightsighter]

Moving this over to the prof-viewer repo and assigning myself.

[elliottslaughter]

This isn't a function of the frontend, which just displays what the backend tells it to.

We need to change the data source implementation to stop being naive in how it uses proc_in_node: https://gitlab.com/StanfordLegion/legion/-/blob/master/tools/legion_prof_rs/src/backend/data_source.rs#L281