iwa: Integrate Key Rotation bits with chrome://web-app-internals

This CL allows developers to initiate custom key rotations as well as
inspect current key rotation data in the json index.

https://screenshot.googleplex.com/4zjnKyHg8jb9CAq is the UI snippet.

Bug: 361276543
Change-Id: Ia585a542e4d0f2b29ba821f1bdce3c8215c6f2dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5803621


Reviewed-by: Dibyajyoti Pal <dibyapal@chromium.org>
Reviewed-by: Elly FJ <ellyjones@chromium.org>
Reviewed-by: Robbie McElrath <rmcelrath@chromium.org>
Commit-Queue: Andrew Rayskiy <greengrape@google.com>
Cr-Commit-Position: refs/heads/main@{#1348027}