[Autofill Assistant] Hides the keyboard during execution.

When Autofill Assistant is running the keyboard shouldn't be shown.
The only exceptions from this rule are:
* Focus action
* Asking for CVC
* During Payment Request

The current solution is imperfect. We only detect once the keyboard
was shown and hide it. We should find eventually better solution to
disable it permanently.

Bug: 806868
Change-Id: I85641652f8c43ec6d3ddb59742510ff793f7f901
Reviewed-on: https://chromium-review.googlesource.com/c/1371814
Commit-Queue: Lukasz Suder <lsuder@chromium.org>
Reviewed-by: Stephane Zermatten <szermatt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615897}
13 files changed