Include Calibration and Statistics PVs as Screen Properties

[eloiseyang]

Is your feature request related to a problem? Please describe.
The profile monitor GUI needs to calibrate screens and broadcast computed beam statistics. It needs to read and write to several different PVs to accomplish these tasks.

Describe the solution you'd like
The screen class should include new properties that automatically read/write to the relevant PVs and throw meaningful errors if the PVs are inaccessible. The YAML files should store the relevant PVs
to simplify handling different screen types. The relevant PVs are listed below. This list is likely incomplete.

• Image Size PV
• ROI PVs
• Resolution PVs
• xmean and ymean positions
• rms positions

[MattKing06]

Some of these have been handled in #127 but we were unable to find the relevant PVs for some screens. It might involve running the yaml generation script again and seeing if the meme service has updated these screens with PVs.