Merge branch '785-verify-maintenance-mode-with-graphql-reimplement-maintenance-mode-handling' into 'master'

Resolve "Verify maintenance mode with GraphQL / reimplement maintenance mode handling"

Closes #785

See merge request !1154

Translations update from Weblate

See merge request !1175

Update translation files

See merge request !1182

Reformat

See merge request !1181

Set related name on site reference of ExtensibleModel to '+'

See merge request !1180

Use Django's session write-through cache

See merge request !971

# Conflicts:
#   CHANGELOG.rst

# Conflicts:
#   CHANGELOG.rst

Resolve "Add route permission for signup page"

Closes #793

See merge request !1168

Resolve "Twilio integration is broken due to the usage of wrong settings"

Closes #801

See merge request !1179

(cherry picked from commit 941e51cc)

Resolve "Add mechanism for apps to dynamically inject menu items"

Closes #797

See merge request !1172

Use original language name plus code in selection menu

See merge request !1173

Update dependency django-cleanup to v7

See merge request !1176

Reformat

See merge request !1177

Resolve "Permission check in searchbar is broken"

Closes #796

See merge request !1171

Resolve "[OAuth] .well-known must be mounted under /"

Closes #606

See merge request !973