This CL enables showing map details of the selected map coming from
FocusEvent. It also improves UI experience of selecting a map from
map transitions, highlighting selected map.

Additionally, stores information about unique map/IC events in model
for the timeline-track legend.

Bug: v8:10644
Change-Id: Ieb8a2ac0bf1af282d55bce18130192d7178538da
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2387564Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Commit-Queue: Zeynep Cankara <zcankara@google.com>
Cr-Commit-Position: refs/heads/master@{#69673}