feat: Support for ext. Multiplex MLink JR type module (#3352)

* introducing external MLink module telemetry as module PPM subtype

* implemented fix for sensor discovery display not showing all detected sensors (is in separate PR too)

implemented PPM subtypes in Companion

* add PPM subtype to model printer

finalize subtypes for PPM in Companion

* added logic to try to use HW UART with inverters turned off first (e.g. NV14), then, if not successfull use soft serial inverted (== uninverted data due to HW inverters on PCB)

changed start bit detection IRQ priority from 5 to the previous 0 (also in separate PR)

* extended telemetry timeout to 2s due to slow Mlink RSSI update rate

* changed the "NOTLM" sub-type texts to:

- "No Telem" for 128x64 (this is the max numbers of characters it can take)
- "No Telemetry" everything else including Companion

* Companion:

- lower case 1st charachter on PpmSubTypeStrings to ppmSubTypeStrings
- added telemetry hooks for ppmSubTypeStrings stringx

* simplified serial port initialization for MLink telemetry

* editorial change: corrected obsolete comment

radio/src/telemetry/telemetry_sensors.cpp

@@ -564,7 +564,9 @@ int setTelemetryValue(TelemetryProtocol protocol, uint16_t id, uint8_t subId,
       case PROTOCOL_TELEMETRY_HOTT:
         hottSetDefault(index, id, subId, instance);
         break;
+#endif
 
+#if defined(MULTIMODULE) or defined(PPM)
       case PROTOCOL_TELEMETRY_MLINK:
         mlinkSetDefault(index, id, subId, instance);
         break;