Add "Join" meeting button to calendar events.

This CL adds a "Join" meeting button that will launch Google Meet, if one is linked to the meeting. If there is no Google Meet meeting linked, then the button will not be added to the view hierarchy.

If the Google Meet app is installed, it will launch in that, otherwise it will launch in the browser.

Screenshot: http://shortn/_B8OBKpTU07

Bug: b/266537227
Change-Id: I459e3a2e9214032ef51d18bbc46f0312f4ee0401
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4224684
Reviewed-by: Jiaming Cheng <jiamingc@chromium.org>
Reviewed-by: Yulun Wu <yulunwu@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Commit-Queue: Sam Cackett <samcackett@google.com>
Reviewed-by: David Roger <droger@chromium.org>
Reviewed-by: Jimmy Gong <jimmyxgong@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1107380}