Implement plans to control the piezos on the focusing mirrors

[noemifrisina]

Closes #110

Needs Dodal#1775

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.07%. Comparing base (cecb42c) to head (cf4d6a7).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #111      +/-   ##
==========================================
+ Coverage   96.91%   97.07%   +0.15%     
==========================================
  Files          21       22       +1     
  Lines         421      444      +23     
==========================================
+ Hits          408      431      +23     
  Misses         13       13              

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[DominicOram]

It would be nice if we can make it so that there doesn't have to be specific plans for this and they could just call run_plan("mv", "vfm-piezo", 100). Especially if they want to be able to scan it at some point too. I'm not sure how we would get this to work with the check_access though, it would need thought

[noemifrisina]

They're not going to want to scan this anytime soon (or ever as things stand, but leaving some leeway for changing their minds) so at least there's some time to think about that.

I've tried the only one plan solution but I couldn't think of any clean way - happy for any suggestion!