Feature/cb2 19647 - Add Vehicle Load Status to Test Result schema in NOP

[meys-bjss]

Description

Introduce a new field in both VTA and VTM to record the mandatory capture of vehicle load status for a HGV or trailer when presented for a full annual test or when conducting an annual retest when the retest has IM numbers 59, 71, 72 and/or 73 or full prohibition ( with or without certificates). This field should capture whether the vehicle/trailer is:

• Unladen
• Partially laden
• Partially laden 50% to 65%
• Fully laden
• Load simulated partially laden
• Load simulated fully laden

Include a summary of the change here.

Added functions and tests for vehicle load status

Related issue: CB2-19647

Before submitting (or marking as "ready for review")

• Does the pull request title follow the conventional commit specification?
• Have you performed a self-review of the code
• Have you have added tests that prove the fix or feature is effective and working
• Did you make sure to update any documentation relating to this change?

[jackanderson02]

Have cherry picked the specific vehicle load status commits to a separate branch. PR here: #138 (review)
Left my feedback on there