system_api: Add `force_fw_update` field

.. to UpdateCheckParams to allow clients/callers into update_engine to
force a FW update.

BUG=b:228121045
TEST=emerge

Change-Id: I4fe391fac328841046c7a88c106a56c03b8d408c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/4119740
Reviewed-by: Henry Barnor <hbarnor@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Jae Hoon Kim <kimjae@chromium.org>
Commit-Queue: Jae Hoon Kim <kimjae@chromium.org>
NOKEYCHECK=True
GitOrigin-RevId: cfa626a0843f32389c6a0134277289aeab5b7aab
diff --git a/dbus/update_engine/update_engine.proto b/dbus/update_engine/update_engine.proto
index d19fef0..07fd7fb 100644
--- a/dbus/update_engine/update_engine.proto
+++ b/dbus/update_engine/update_engine.proto
@@ -142,6 +142,9 @@
 
   // Checks for an update, but does not apply it.
   bool skip_applying = 4;
+
+  // Forces a fw update with OS update.
+  bool force_fw_update = 5;
 }
 
 message InstallParams {