gd: Add uma metrics 1/n

This CL adds metrics for ways to toggle on/off the GD main menu.
    - clicking GD button.
    - pressing accelerator keys.
    - pressing key Esc.
    - activating new feature.
    - entering overview mode.
    - clicking outside of the main menu or closing the game window.

(Check go/gd-metrics for metrics plan.)

Bug: b/273640775
Test: ash_unittests --gtest_filter="*GameDashboardContext*"
Change-Id: Ib5f85bfdf610f3b98f16cdd2a565316b392628dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5311291
Commit-Queue: Cici Ruan <cuicuiruan@google.com>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Reviewed-by: Prameet Shah <phshah@chromium.org>
Reviewed-by: Yulun Wu <yulunwu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1266135}