Add MbsDetector, remove unneeded EnergySource logic

[oliwenmandiamond]

Fixes #2070

Instructions to reviewer on how to test:

1. Check tests pass
2. Implementation makes sense

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 99.14%. Comparing base (f787f83) to head (153fde4).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2071      +/-   ##
==========================================
- Coverage   99.14%   99.14%   -0.01%     
==========================================
  Files         341      342       +1     
  Lines       13287    13281       -6     
==========================================
- Hits        13173    13167       -6     
  Misses        114      114              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.