Protected packages: Add REST API for package protection rules

Context

• As part of the epic &5574 , project maintainer or owner need to have a way to define the PackageProtectionRules of the project via REST API
• At the moment, there is a GraphQL API and a frontend UI that can be used to CRUD package protection rules; however, the REST API is important because some tools clients are not able to use the GraphQL API, e.g. terraform, etc.

🛠 with ❤ at Siemens

Proposal

• Authorization: PackageProtectionRules can only changed by project maintainer or higher => consider implementation with declarative framework
• Endpoint route: api/v4/projects/:id/packages/protection/rules

REST Endpoint	MR
GET api/v4/projects/:id/packages/protection/rules	!153436 (merged)
POST api/v4/projects/:id/packages/protection/rules	!153571 (merged)
PATCH api/v4/projects/:id/packages/protection/rules	!153577 (merged)
DELETE api/v4/projects/:id/packages/protection/rules	!151741 (merged)

Checklist / Implementation plan

• Protected packages: REST API GET package protec... (!153436 - merged)
• Protected packages: REST API POST package prote... (!153571 - merged)
• Protected packages: REST API PATCH package prot... (!153577 - merged)
• Protected packages: REST API DELETE package pro... (!151741 - merged)