More displayPort_t, CANVAS as new feature, multi-display cycling

- Further touch-ups with displayPort_t handling.
- CANVAS is a FEATURE now.
- Device specific xxxCmsInit() are registered by device’s init, and
called by CMS upon entry to menu.
- Multiple display devices can be cycled by entering menu invocation
command while in menu.
- The menu invocation command is (was) changed to THR-Mid + YAW-Left +
Pitch-Full to avoid collision with MWOSD menu invocation command.
- More separation attempt.

src/main/io/serial_cli.c

@@ -227,7 +227,7 @@ static const char * const featureNames[] = {
     "SONAR", "TELEMETRY", "CURRENT_METER", "3D", "RX_PARALLEL_PWM",
     "RX_MSP", "RSSI_ADC", "LED_STRIP", "DISPLAY", "OSD",
     "BLACKBOX", "CHANNEL_FORWARDING", "TRANSPONDER", "AIRMODE",
-    " ", "VTX", "RX_SPI", "SOFTSPI", NULL
+    " ", "VTX", "RX_SPI", "SOFTSPI", "CANVAS", NULL
 };
 
 // sync this with rxFailsafeChannelMode_e