[DeviceStruct] Add setting for Allowed Serial Ports

[tonhuisman]

Features:

• Add a configuration item SerialPortsAllowed to DeviceStruct so the allowed serial ports (HW Serial, SW Serial, I2C Serial, (HW)CDC Serial) can be limited to what's technically feasible. When not set, all types of serial ports are available (as it was until now).
• [P054] Limit to serial ports that use on-chip GPIO pins (HW & SW Serial).
• [P065] Don't allow (HW)CDC Serial port selection.
• [P077] Only HW Serial ports allowed.
• [P159] Don't allow (HW)CDC Serial port selection.

TODO:

• Testing
• Update documentation where needed