Add i21 sample stage

[oliwenmandiamond]

Fixes #ISSUE

Instructions to reviewer on how to test:

1. Do thing x
2. Confirm thing y happens

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 99.16%. Comparing base (e13e2a2) to head (3bce99b).

Additional details and impacted files

@@                    Coverage Diff                    @@
##           add_sample_stage_for_i05    #1888   +/-   ##
=========================================================
  Coverage                     99.15%   99.16%           
=========================================================
  Files                           308      309    +1     
  Lines                         11578    11674   +96     
=========================================================
+ Hits                          11480    11576   +96     
  Misses                           98       98           

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