[v16.x backport] test: add WPTRunner support for variants and generating WPT reports
Backports #46498, #46778, and #46804 to v16.x.
Enables WPT Report for future v16.x LTS releases.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Backports #46498, #46778, and #46804 to v16.x.
Enables WPT Report for future v16.x LTS releases.