[roll] Roll fuchsia [isolated_devmgr][v2] Minor improvements

* Add driver-manager-test (i.e. the driver manager logic) `dep` for
  generated `isolated_devmgr_v2_component`s so that clients don't need
  to explicitly include the dep themselves.
* Remove typo(?) reference to devmgr_args.
* Add doc comment for the GN template.

Test: `$ fx test pkg-cache-integration-tests`, which make direct usage
      of the v2 IsolatedDevmgrComponent, to verify nothing is broken.
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/504562
Original-Revision: 7dbad212abfd7b43f58df53a58b98fd869aabee1
GitOrigin-RevId: 8750c9f05185012394ada6c6d4e3375be2bd4754
Change-Id: Ife7147d1bc0266594801a985bb56189582440572
diff --git a/stem b/stem
index 7bfb8aa..d498086 100644
--- a/stem
+++ b/stem
@@ -10,7 +10,7 @@
              githooks=""
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="b9f0319e96a10d8940cda4e91616abe87623dafa"/>
+             revision="7dbad212abfd7b43f58df53a58b98fd869aabee1"/>
   </projects>
   <hooks>
     <hook name="install-environment"