feat: add template version creator (#2991)

coderd/database/migrations/000030_template_version_created_by.down.sql

@@ -0,0 +1 @@
+ALTER TABLE ONLY template_versions DROP COLUMN IF EXISTS created_by;

coderd/database/migrations/000030_template_version_created_by.up.sql

@@ -0,0 +1,14 @@
+ALTER TABLE ONLY template_versions ADD COLUMN IF NOT EXISTS created_by uuid REFERENCES users (id) ON DELETE RESTRICT;
+
+UPDATE
+    template_versions
+SET
+    created_by = (
+        SELECT created_by FROM templates
+        WHERE template_versions.template_id = templates.id
+        LIMIT 1
+    )
+WHERE
+    created_by IS NULL;
+
+ALTER TABLE ONLY template_versions ALTER COLUMN created_by SET NOT NULL;