Add transmission module for I19 beamline devices

[CoePaul]

• Start with adding JSON validation for system specification JSON dict-like structure expectations

• Pydantic BaseModel classes map sub-structures ( sub-dicts ) within the system description structure here adding JSON validation for energy_interval [ the range of x-ray energies (in keV ) over which an absorption curve is valid ] JSON validation for absorption fit curve parameters [ the scaling constant, roll-off vs energy and an optional residuals polynomial ]

Fixes #2199

Instructions to reviewer on how to test:

1. Check criteria from issue # 2199 are met
2. Confirm CI passes tests and linter is happy

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 99.34%. Comparing base (7b8fff3) to head (6ec9d9e).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2200   +/-   ##
=======================================
  Coverage   99.34%   99.34%           
=======================================
  Files         367      370    +3     
  Lines       14396    14436   +40     
=======================================
+ Hits        14301    14341   +40     
  Misses         95       95           

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