add versions to the provider schemas

We need to know the schema version for all resources. This is stored in
order to allow providers to upgrade the state from a known previous
version.

providers/provider.go

@@ -66,18 +66,25 @@ type Interface interface {
 
 type GetSchemaResponse struct {
 	// Provider is the schema for the provider itself.
-	Provider *configschema.Block
+	Provider Schema
 
 	// ResourceTypes map the resource type name to that type's schema.
-	ResourceTypes map[string]*configschema.Block
+	ResourceTypes map[string]Schema
 
 	// DataSources maps the data source name to that data source's schema.
-	DataSources map[string]*configschema.Block
+	DataSources map[string]Schema
 
 	// Diagnostics contains any warnings or errors from the method call.
 	Diagnostics tfdiags.Diagnostics
 }
 
+// Schema pairs a provider or resource schema with that schema's version.
+// This is used to be able to upgrade the schema in
+type Schema struct {
+	Version int
+	Block   *configschema.Block
+}
+
 type ValidateProviderConfigRequest struct {
 	// Config is the complete configuration value for the provider.
 	Config cty.Value