Reland "Privacy Review: implement UI elements for the footer."

This is a reland of c1e958e4

Fixed missing include that broke the optimize_webui=false configuration.

Original change's description:
> Privacy Review: implement UI elements for the footer.
>
> This patch splits the privacy review footer into three elements, one for
> each of the welcome screen, completion screen, and settings cards, and
> creates the basic UI elements for each. It also reimplements
> welcome/shared/step_indicator.ts for settings, so that it can be used in
> the settings cards' footer.
>
> Bug: 1215630
> Change-Id: I2f88bc6f022ee9b1cc1e0b825409cb2a6f90122a
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3093811


> Commit-Queue: Bret Sepulveda <bsep@chromium.org>
> Reviewed-by: Jimmy Gong <jimmyxgong@chromium.org>
> Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
> Reviewed-by: Rainhard <rainhard@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#914679}

Bug: 1215630
Change-Id: Iad2b4e5bed5a5313180e986bee7a84f9de70ef2b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3115987


Reviewed-by: Rainhard <rainhard@chromium.org>
Reviewed-by: Jimmy Gong <jimmyxgong@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/main@{#915096}