Add automated test for "AppWithinMinutes parent"

The manual test is here: https://test.xwiki.org/xwiki/bin/view/Administration%20Tests/AppWithinMinutes%20parent

The test verifies that the default location of an AWM app is at the wiki root, even if the home page is changed on a wiki.

The matrix discussions:

https://matrix.to/#/!ikPtGZaGWtyblizzlR:matrix.xwiki.com/$160424523530ccOEL:matrix.xwiki.com?via=matrix.org&via=matrix.xwiki.com&via=t2bot.io

https://matrix.to/#/!ikPtGZaGWtyblizzlR:matrix.xwiki.com/$1604304153394SzpFX:matrix.xwiki.com?via=matrix.org&via=matrix.xwiki.com&via=t2bot.io

https://matrix.to/#/!ikPtGZaGWtyblizzlR:matrix.xwiki.com/$16043329402808mcxYe:matrix.xwiki.com?via=matrix.org&via=matrix.xwiki.com&via=t2bot.io