Add devices for VMXM ispyb gridscan info

[olliesilvester]

These devices are used for ispyb metadata when doing grid scans.

Currently this doesn't connect because the prefix on vmxm's flux PV is different to that of the common device.

Instructions to reviewer on how to test:

1. check dodal connect i02_1 on this branch

Checks for reviewer

• Would the PR title make sense to a scientist on a set of release notes
• If a new device has been added does it follow the standards
• If changing the API for a pre-existing device, ensure that any beamlines using this device have updated their Bluesky plans accordingly
• Have the connection tests for the relevant beamline(s) been run via dodal connect ${BEAMLINE}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.12%. Comparing base (dd687cc) to head (c64c3e7).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1925   +/-   ##
=======================================
  Coverage   99.12%   99.12%           
=======================================
  Files         331      331           
  Lines       12886    12913   +27     
=======================================
+ Hits        12773    12800   +27     
  Misses        113      113           

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[rtuck99]

Approved

Changes addressed