feat: Add backend API support for resource metadata (#3242)

* Initial support for metadata in provisioner API and Terraform provisioner

* add support for nullable metadata fields

* handle metadata fields in provisionerd and API

site/src/api/typesGenerated.ts

@@ -517,6 +517,14 @@ export interface WorkspaceResource {
   readonly type: string
   readonly name: string
   readonly agents?: WorkspaceAgent[]
+  readonly metadata?: WorkspaceResourceMetadata[]
+}
+
+// From codersdk/workspaceresources.go
+export interface WorkspaceResourceMetadata {
+  readonly key: string
+  readonly value: string
+  readonly sensitive: boolean
 }
 
 // From codersdk/workspacebuilds.go