[Autofill Assistant] Added possibility to click via javascript.

This CL refactors clicks in web_controller such that the caller can specify one of a number of click-types (click, tap, JS-click). Also, this CL adds three stress-tests which fail for tap, but succeed in JS-click.

The intent is to let scripters override the type of click to perform in order to increase reliability.

Bug: b/133129236
Change-Id: Ied8a1145186e1277c5b0cd70bb433b723a9a7395
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1621919
Commit-Queue: Clemens Arbesser <arbesser@google.com>
Reviewed-by: Mathias Carlen <mcarlen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662628}
12 files changed