[compose] Make expandable menu icon depend on suggestion type

Another option could be to make the expandable icon a property of the
suggestion struct. However since for now this is tied to a popup item
id (and I believe it will always be), it is cleaner to make the
decision based on it.

Design: https://screenshot.googleplex.com/BUyAFBrNgKWHMYY
Demo: https://screenshot.googleplex.com/6xstBwFU5s9CVY2

Note: It seems like the design has a bold icon style,
I will ask the compose team whether this is indeed the case.
If so, we can update it accordingly, such update would not affect
what is done in this CL and would likely entail optionally applying
a icon style also depending on the popup item id.

Bug: b/333929225
Change-Id: Id7fcf227c9046d14016094caf9e666658cacb6f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5471624
Reviewed-by: Jan Keitel <jkeitel@google.com>
Commit-Queue: Bruno Braga <brunobraga@google.com>
Cr-Commit-Position: refs/heads/main@{#1291805}