* Add Initializer to the controller
The Initializer adds support for running any required initialization
steps when the controller is first started.
* Implement HCP Link initializer
The link initializer will create a Link resource if the
cloud configuration has been set.
* Simplify retry logic and testing
* Remove internal retry, replace with logging logic
* Add HCCLink resource type
* Register HCCLink resource type with basic validation
* Add validation for required fields
* Add test for default ACLs
* Add no-op controller for HCCLink
* Add resource-apis semantic validation check in hcclink controller
* Add copyright headers
* Rename HCCLink to Link
* Add hcp_cluster_url to link proto
* Update 'disabled' reason with more detail
* Update link status name to consul.io/hcp/link
* Change link version from v1 to v2
* Use feature flag/experiment to enable v2 resources with HCP