Rule for github_repository seems to be wrongly placed under gcp

[HorizonNet]

The rule accurics.gcp.IAM.145 is currently located under gcp, which isn't intuitive as it is targeting the GitHub provider and not GCP. It would be better to move its own policy set.

[williepaul]

@HorizonNet Agreed--the policy is written for that provider specifically. I think for now we may want to keep two copies of the rule, one in a provider-specific folder, and the original one. Ideally, probably it'll be helpful just to detect all providers used and enable the corresponding policies by default.

[HorizonNet]

Added a first draft for the provider. Some points are probably still missing. Started by trying to simulate what was done for the gcp policies.