Add more validations to linter

- Ensure all variables and outputs are sorted
- Ensure all variables and outputs have a description
- Add data-solutions/data-platform-foundations to linter

Fix all modules to follow these new conventions.

modules/source-repository/variables.tf

@@ -14,11 +14,6 @@
  * limitations under the License.
  */
 
-variable "project_id" {
-  description = "Project used for resources."
-  type        = string
-}
-
 variable "iam" {
   description = "IAM bindings in {ROLE => [MEMBERS]} format."
   type        = map(list(string))
@@ -29,3 +24,8 @@ variable "name" {
   description = "Repository name."
   type        = string
 }
+
+variable "project_id" {
+  description = "Project used for resources."
+  type        = string
+}