feat(coderd/database): add value_key_id column to user_secrets for encryption (#23997)

Add a nullable `value_key_id` column to the `user_secrets` table with a
foreign key to `dbcrypt_keys`. This is the column dbcrypt uses to track
which encryption key encrypted a given secret's value. This is required
for encryption of user secret values.

The column was missing from the original migration (000357).

coderd/database/dump.sql

@@ -2808,7 +2808,8 @@ CREATE TABLE user_secrets (
     env_name text DEFAULT ''::text NOT NULL,
     file_path text DEFAULT ''::text NOT NULL,
     created_at timestamp with time zone DEFAULT CURRENT_TIMESTAMP NOT NULL,
-    updated_at timestamp with time zone DEFAULT CURRENT_TIMESTAMP NOT NULL
+    updated_at timestamp with time zone DEFAULT CURRENT_TIMESTAMP NOT NULL,
+    value_key_id text
 );
 
 CREATE TABLE user_status_changes (
@@ -4306,6 +4307,9 @@ ALTER TABLE ONLY user_links
 ALTER TABLE ONLY user_secrets
     ADD CONSTRAINT user_secrets_user_id_fkey FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE;
 
+ALTER TABLE ONLY user_secrets
+    ADD CONSTRAINT user_secrets_value_key_id_fkey FOREIGN KEY (value_key_id) REFERENCES dbcrypt_keys(active_key_digest);
+
 ALTER TABLE ONLY user_status_changes
     ADD CONSTRAINT user_status_changes_user_id_fkey FOREIGN KEY (user_id) REFERENCES users(id);