Replace nested types.ResourceSchema with types.SingleNestedBlock / types.ObjectType

[alexmingoia]

Terraform's new import blocks feature doesn't handle nested resource schemas.

Rootly's Terraform provider was written before Terraform 1.3 to support 0.14+. Before version 1.3, Terraform lacked support for nested objects in schemas. Nested object schemas were added in TF 1.3 (types.SingleNestedBlock + types.ObjectType ). Their workaround at the time was to use nested resources. The trigger_params and task_params attribute schemas are defined as types.ResourceSchema. It seems Terraform's import blocks don't handle this old workaround correctly.

What we can do is release a new provider requiring minimum of TF 1.3+, rewriting nested objects with old type types.ResourceSchema with the new types.SingleNestedBlock + types.ObjectType .