sources/oauth: Add Mailcow oauth source (#2380)

* Feat: Add Mailcow oauth source

* Feat: Add mailcow icon

* Run make

* Feat: Add tests

* Fix: Remainder from discord test

* Docs: Add mailcow oauth source docs

* Docs: add mailcow source to menu

* Fix: Mailcow provider type in test

* Fix: Formatting

* Fix: Doc file name

website/sidebarsIntegrations.js

@@ -60,6 +60,7 @@ module.exports = {
                 "sources/github/index",
                 "sources/google/index",
                 "sources/ldap/index",
+                "sources/mailcow/index",
                 "sources/oauth/index",
                 "sources/plex/index",
                 "sources/saml/index",