Merge branch '835-notifaction-send-always-creates-celery-task-with-force-sending' into 'release-3.0'

Resolve "Notifaction.send always creates Celery task with force sending"

See merge request !1212

Merge branch 'release-3.0' into '835-notifaction-send-always-creates-celery-task-with-force-sending'

# Conflicts:
#   CHANGELOG.rst

Resolve ""Retry" button opens about:blank in new tab"

See merge request !1220

# Conflicts:
#   CHANGELOG.rst

Merge branch '846-query-strings-do-not-get-passed-when-navigating-legacy-pages-in-spa' into 'release-3.0'

Resolve "Query strings do not get passed when navigating legacy pages in SPA"

See merge request !1222

Resolve "Fix cachalot issues (aka upgrade cachalot)"

See merge request !1221

Resolve "Move DeleteDialog from Plank to Core"

See merge request !1207

# Conflicts:
#   CHANGELOG.rst

Merge branch '838-offline-fallback-page-for-django-legacy-pages-is-misleading-in-some-situations' into 'release-3.0'

Resolve "Offline fallback page for django legacy pages is misleading in some situations"

See merge request !1215

Merge branch 'release-3.0' into 838-offline-fallback-page-for-django-legacy-pages-is-misleading-in-some-situations

Resolve "Scroll to top when route changes inside iframe"

See merge request !1214

# Conflicts:
#   CHANGELOG.rst

Resolve "`Stop impersonation` Button missing"

See merge request !1213

Improve lifecycle of SPA

See merge request !1211

Resolve "Supply Room ID and Name via Graphql"

See merge request !1202