picodb(mssql): support all MSSQL pdo drivers

For MSSQL make all connection attributes optional.
Handle differing DB connection params based on driver used.
connection can be made via ODBC DSN or server/hostname
username/password can be embedded in DSN definition or simply
omitted and single-signon will be attempted.

libs/picodb/lib/PicoDb/DriverFactory.php

@@ -32,6 +32,10 @@ class DriverFactory
         switch ($settings['driver']) {
             case 'sqlite':
                 return new Sqlite($settings);
+            case 'odbc':
+                return new Mssql($settings);
+            case 'dblib':
+                return new Mssql($settings);
             case 'mssql':
                 return new Mssql($settings);
             case 'mysql':