Add ability to create databases and databases_grants to postgresql::server

[rayderua]

postgresql::server_instance can manage databases and grants

Hash $databases_and_users                         = {},
Hash $databases                                   = {},
Hash $database_grants                             = {},
Hash $table_grants                                = {},

But we cannot create databases and/or grants via postgresql::server, so we must write wrappers/profiles around module.
Would be great if we can create them via postgresql::server,, like in postgresql::server_instance

[ikonia]

#1668

sorts grants

[ikonia]

managing permissions to roles is proving harder, but grants and database creation is fixed into those 2 PR's