Revert "[Autofill Assistant] Refactor of payment request UI."

This reverts commit 2f44a657fad02ae6b5ec4d455d97a250184a4e82.

Reason for revert: Just a quick revert to allow http://crrev/c/1583782 to land before this change, as that one will be merge-requested to M-75.

Original change's description:
> [Autofill Assistant] Refactor of payment request UI.
> 
> This CL refactors the Autofill Assistant PR UI. The goal is to make the new UI modular (because parts of it will be used outside the PR) and more easily customizable.
> 
> To this end, this CL introduces two new custom widgets:
>  - AssistantVerticalExpander is a widget container with a title and a chevron-icon to toggle between a 'collapsed' and 'expanded' state. It is intended to be used in all PR sections.
>  - AssistantVerticalExpanderAccordion is a linear layout which automatically ensures that a maximum of one of its child expanders is expanded at the same time. If an expander is expanded, all others are automatically collapsed. The accordion can otherwise be used just like a linear layout.
> 
> This CL also introduces the necessary classes to facilitate translation between Chrome PR (SectionInformation) and the new AA UI.
> 
> Bug: 806868
> Bug: 1538294
> Binary-Size: Added new UI widgets for use in the Autofill Assistant PR UI.
> Change-Id: I432398c773e5329dc8aec553a71be72784b8ad97
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1538294
> Commit-Queue: Clemens Arbesser <arbesser@google.com>
> Reviewed-by: Stephane Zermatten <szermatt@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#654015}

TBR=szermatt@chromium.org,jdemeulenaere@chromium.org,arbesser@google.com

Change-Id: I16c5e7815e30f7a82bb6f22667d5961af2860e6f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 806868, 1538294
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1584300
Reviewed-by: Clemens Arbesser <arbesser@google.com>
Commit-Queue: Clemens Arbesser <arbesser@google.com>
Cr-Commit-Position: refs/heads/master@{#654022}
26 files changed