Bug 1754817 [wpt PR 32803] - [dPWA] Sub Apps - add code for list() API, a=testonly

Bug 1754817 [wpt PR 32803] - [dPWA] Sub Apps - add code for list() API, a=testonly

Automatic update from web-platform-tests
[dPWA] Sub Apps - add code for list() API

This CL adds the functionality for listing sub-apps that were added by
the parent app that is calling the API.

Sub Apps API enables PWAs to create multiple launch icons with distinct
names.

Design doc: go/multi-apps (draft)

Bug: 1171317
Change-Id: I9f7ec0721987757397b58c7e43930f0291e7b6c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3307062
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Reviewed-by: Phillis Tang <phillis@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Ivan Šandrk <isandrk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#971227}

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wpt-commits: cb0004e12583ff06865a92dadfc87af3078c0138
wpt-pr: 32803