Refactor Provider To Work Like AWS eks_cluster_auth datasource

[markekibbe]

BUSINESS PROBLEM
Using two providers for Venafi seemes duplicative and counter-intuitive vs other approaches, such as AWS eks_cluster_auth authentication options.

PROPOSED SOLUTION

• Solution 1: Refactor this provider capability into a datasource, on the original venafi provider. The existing authentication can be utilized as a datasource input with alias's if desired, or, internally handle the authentication via oauth asking for the properties, making it more transparent to the user.

• Solution 2: Refactor this capability into a datasource on this provider, removing the need to "import", and setup the provider authentication to require the oauth values needed to produce the authentication, allowingthis datasource to be fed into the primary provider as seen here: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/eks_cluster_auth

CURRENT ALTERNATIVES
No current solution

VENAFI EXPERIENCE
Currently working as an integrator, and am new to the Venafi platform but have experience working with tens of terraform providers for various solutions ranging from Azure, AWS, GitLab, GitHub, Okta, and several others. Also am HashiCorp Terraform Associate Certified.