Add `occ user:welcome` command to send user welcome email from CLI #9194

Job	Run time
changes	7s
integration-sqlite (capabilities_features, 8.2, main)	5m 3s
integration-sqlite (collaboration_features, 8.2, main)	7m 31s
integration-sqlite (comments_features, 8.2, main)	6m 22s
integration-sqlite (dav_features, 8.2, main)	10m 39s
integration-sqlite (features, 8.2, main)	11m 42s
integration-sqlite (federation_features, 8.2, main)	2m 28s
integration-sqlite (--tags ~@large files_features, 8.2, main)	11m 49s
integration-sqlite (filesdrop_features, 8.2, main)	5m 45s
integration-sqlite (openldap_features, 8.2, main)	5m 26s
integration-sqlite (openldap_numerical_features, 8.2, main)	4m 46s
integration-sqlite (ldap_features, 8.2, main)	5m 48s
integration-sqlite (remoteapi_features, 8.2, main)	5m 27s
integration-sqlite (setup_features, 8.2, main)	5m 22s
integration-sqlite (sharees_features, 8.2, main)	8m 5s
integration-sqlite (sharing_features, 8.2, main)	14m 46s
integration-sqlite (videoverification_features, 8.2, main)	8m 19s
integration-sqlite-summary	5s
	1h 59m 30s

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