Add Container Registry API

[PhilippeVienne]

Pull request to resolve: #367

• Implement Container Registry API following documentation
• Add Documentation about API on readme
• Implement Testing for the API

[gmessner]

@PhilippeVienne
It is highly unusual to have form data with the DELETE method. Have you tried this with query params?

[PhilippeVienne]

I was just following the curl request set as example on the GitLab documentation. I will have a try with params.

[gmessner]

@PhilippeVienne
Let me know how it goes. If it requires form data, I'll add a delete() method that accepts form data.

[PhilippeVienne]

My local test have correctly a 202 Accepted response but the bulk DELETE seems to fail in all situation, as stated by documentation and also as you suggested with Query Params

[gmessner]

@PhilippeVienne
I forgot to thank you for your contribution, so thank you.

I am going to go ahead and merge this PR. Once merged, I'll look into and implement the bulk delete functionality. I will also create the TestContainerRegistryApi test class but would like to work with you to fully implement the integration tests for this. Will provide more information later today.

[gmessner]

@PhilippeVienne
The bulk tag delete is working correctly using query parameters, what I did find out is that if you call the bulk delete API endpoint more than once in an hour, the GitLab server simply responds with a 202 status and does absolutely nothing. It does work on the first use though or done less than once an hour. The “at most once an hour” is mentioned in the GitLab documentation (https://docs.gitlab.com/ee/api/container_registry.html#delete-repository-tags-in-bulk)