chore: track usage of built-in example templates (#15671)

Addresses https://github.com/coder/nexus/issues/99.

Changes:
- Save the id of the built-in example template used to create a template
version in the database
- Include the example id in telemetry

coderd/database/queries/templateversions.sql

@@ -87,10 +87,11 @@ INSERT INTO
 		message,
 		readme,
 		job_id,
-		created_by
+		created_by,
+		source_example_id
 	)
 VALUES
-	($1, $2, $3, $4, $5, $6, $7, $8, $9, $10);
+	($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11);
 
 -- name: UpdateTemplateVersionByID :exec
 UPDATE