Add signals for current puck and pin

[DominicOram]

See DiamondLightSource/mx-bluesky#240

Instructions to reviewer on how to test:

1. Run dodal connect i03 and confirm new signals connect

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 94.90%. Comparing base (212141f) to head (040a728).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #785   +/-   ##
=======================================
  Coverage   94.90%   94.90%           
=======================================
  Files         115      115           
  Lines        4654     4656    +2     
=======================================
+ Hits         4417     4419    +2     
  Misses        237      237           

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[rtuck99]

Approved