Use factory pattern for ESPDevice making calls to connect cleaner

[mateogianolio]

If we rewrite ESPDevice to a factory class returning subclasses based on input params for transport and security, we can get cleaner method calls to connect (instead of passing null for unused params):

// security 0, ble
device.connect();

// security 0, softAP
device.connect(softAPPassword);

// ... etc