feat: keep original token refresh error in external auth (#19339)

External auth refresh errors lose the original error thrown on the first
refresh. This PR saves that error to the database to be raised on
subsequent refresh attempts

coderd/database/migrations/000358_failed_ext_auth_error.up.sql

@@ -0,0 +1,7 @@
+ALTER TABLE external_auth_links
+	ADD COLUMN oauth_refresh_failure_reason TEXT NOT NULL DEFAULT ''
+;
+
+COMMENT ON COLUMN external_auth_links.oauth_refresh_failure_reason IS
+	'This error means the refresh token is invalid. Cached so we can avoid calling the external provider again for the same error.'
+;