Adding support for multi output models to execute when updated.

In this CL,
Added flow in ResultRefreshManager to execute multi output models when
updated. Currently for multi output model, this works with a hack where
we execute models on update using old flow, but prefs updation requires
couple of sessions.

Due to these changes, model execution will be triggered on model updated
for multi output models. Clearly separated out the flow for multi output
and legacy models. More info on design change: go/modelinfoupdated

Change-Id: I7baebf012afe0097defc73213bdfea51d96e47c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4504296


Reviewed-by: Salvador Guerrero Ramos <salg@google.com>
Reviewed-by: Siddhartha S <ssid@chromium.org>
Commit-Queue: Ritika Gupta <ritikagup@google.com>
Cr-Commit-Position: refs/heads/main@{#1146752}