[roll] Roll fuchsia [tools] Replace `fx set-product` with `fx set --main-product`.

`$FUCHSIA_BUILD_DIR/ffx-config.json` is clobbered in some full
builds, so this value should be set by configuration that ends
up in `args.gn`. This will allow developers to configure it
from `fx set`, `local/args.gn`, or by editing their `args.gn`
directly.

`fx get-device` should continue to work transparently as it
works by reading the ffx config which includes the per-build
config this modifies.

Original-Bug: 356235506
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1132793
Original-Revision: 087d8035cac36aefff825eb28cd34cee10340a77
GitOrigin-RevId: e8b356b08a6ea203dc65bcfd8a8284c1a85c99fc
Change-Id: Iace242e69c7a2c0920a8bdfb32410896f514ede0
diff --git a/stem b/stem
index 1a8d465..fc89666 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="81a89819fd483506795b0f237a23127fdccb6b0f"/>
+             revision="087d8035cac36aefff825eb28cd34cee10340a77"/>
   </projects>
   <hooks>
     <hook name="install-environment"