STXM step scan

[Relm-Arrowny]

Goals

Acceptance criteria :

• [x] Create a plan to do STXM step scan.

Tasks

base on the goals, deduce the tasks required. check them off once they're done

• [x] Create stats only area detector, (no real need to save the ccd image but will require the detector stats to be recorded.
• [x] Define the points/type for the grid scan. Possibly using scanspec](https://github.com/dls-controls/scanspec)
• [x] Does the scan.