Inject mock zebra logic

[DominicOram]

Fixes #1794

Instructions to reviewer on how to test:

1. Confirm downstream tests pass

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 (a1a5829) to head (ea5b0d7).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1801   +/-   ##
=======================================
  Coverage   99.12%   99.12%           
=======================================
  Files         282      282           
  Lines       10683    10691    +8     
=======================================
+ Hits        10589    10597    +8     
  Misses         94       94           

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