Improve authz error messaging for protected licenses

[ezekg]

For example, this should use a specific deny! message, and also use allow!, instead of being implicit with a boolean:

keygen-api/app/policies/license_policy.rb

Lines 90 to 106 in 01dab08

	def check_out?
	verify_permissions!('license.check-out')
	verify_environment!
	case bearer
	in role: Role(:admin | :developer | :sales_agent | :support_agent | :environment)
	allow!
	in role: Role(:product) if record.product == bearer
	allow!
	in role: Role(:user) if record.owner == bearer || bearer.licenses.exists?(record.id)
	!record.protected?
	in role: Role(:license) if record == bearer
	allow!
	else
	deny!
	end
	end

Referring to line 100 above.