Reland "Model validation support"

This is a reland of 155e38f8

Removed the browser tests that were failing in chrome OS, and disabled a
model invalid unittest due to https://crbug.com/1240561

> Model validation support
>
> Introduces a ModelValidator class and adds a command-line switch to
> validate model using ModelValidator. No code is expected to run when the
> command-line switch is not specified.

> Bug: 1219668
> Change-Id: I12f93956b4657bb9997b772a797f1e37d2e99a03
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2999073


> Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
> Reviewed-by: Sophie Chang <sophiechang@chromium.org>
> Commit-Queue: rajendrant <rajendrant@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#908596}

Bug: 1219668
Change-Id: I3cc2727c098891c60e374ccc9758bf3ebb71403f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3138354


Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: rajendrant <rajendrant@chromium.org>
Cr-Commit-Position: refs/heads/main@{#917748}