IAM Role Assignment (#665)

* Initial PoC for a Project Role Assignment resource

Signed-off-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>

* fix: move project_role_assignment into new "authorization" resource group

Signed-off-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>

* feat: add authorization_project_role_assignment acceptance test

Signed-off-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>

* docs: add authorization_project_role_assignment docs and examples

Signed-off-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>

* fix: linting

Signed-off-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>

* feat: add generic role_assignment resources

Signed-off-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>

* feat: add infrastructure for experimental features

Signed-off-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>

* feat: Make IAM resources part of the iam experiment

Signed-off-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>

* fix: Log an error if an experiment does not exist

Signed-off-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>

* fix: Do not cache the experiment check

Caching the experiment check causes problems when
running the provider in debug mode, since
configure in the provider can be called multiple
times there with different configurations, with
different experiments enabled.

Signed-off-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>

---------

Signed-off-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>
Co-authored-by: Benjamin Ritter <benjamin.ritter@stackit.cloud>

stackit/internal/core/core.go

@@ -41,6 +41,7 @@ type ProviderData struct {
 	SKECustomEndpoint               string
 	ServiceEnablementCustomEndpoint string
 	EnableBetaResources             bool
+	Experiments                     []string
 }
 
 // GetRegion returns the effective region for the provider, falling back to the deprecated _region_ attribute