Add patch endpoint, update forms function

• Add PATCH instrument/:slug
• Pre-popluate edit forms with existing data (works for `/update/:slug)
• Submit edit forms with overriding data
• Verify api/db updates correspond
• Updates SAL messages for inserts and updates
• Prunes and updates routes:
  • /, /list = Catalog view
  • /update = Modify Instrument view without prefilling with existing instrument
  • /update/:slug = Modify Instrument view with existing instrument data
  • /template = Start new instrument from Template view (pre-populating on select does NOT work yet)

Bug: T362144