Add Trailer API lifecycle collection

[roncodes]

Summary

• add the first-class Trailer resource definition and object schema
• cover create, query, retrieve, update, track, attach, detach, connection history, and delete
• cover Trailer Device and Equipment attachment, detachment, reassignment, verification, and cleanup
• document polymorphic Device and Equipment attachment parameters

Validation

• npm run postman:lint
• 5 collections and 3 environments validated
• Fleetbase API: 219 requests, 0 errors, 0 warnings

Related PRs

• Fleet-Ops: Add first-class Trailer operations fleetops#309
• fleetops-data: Add first-class Trailer data models fleetops-data#75
• fleetbase.io: Document first-class Trailer operations fleetbase.io#96