Add isConnected to BLEPrinter (Android)

[hkerkhoff]

this adds a isConnected-Function to the Android implementation for BLEPrinter.

It seems as if the connection-Status is not updated when the device looses the connection (so the bluetooth socket still claims its connected).

What I do:

await BLEPrinter.init();
await BLEPrinter.closeConn(); 
if (!(await BLEPrinter.isConnected())) {
      await BLEPrinter.connectPrinter(macAddress);
}

const connected = await BLEPrinter.isConnected();
if (connected) {
      // print stuff
} else {
      // show dialog / handle not connected
}

Feel free to merge, modify or use the my fork https://github.com/hkerkhoff/react-native-thermal-receipt-printer-image-qr with no warranty :)

[thiendangit]

how about ios @hkerkhoff ?

[hkerkhoff]

how about ios @hkerkhoff ?

@thiendangit i'm not an objective-c guy - I added the implementation with help of chatgpt, looks ok for me, but would be great if you can check it :)