feat(nfc): add NFC readerMode

[stephendwolff]

I opened an issue about this #2756, and have managed to add the reader mode in my fork.

Please could you merge my pull request, as it would be good to use the main release in my app

[danielsogl]

Please remove all package changes

[stephendwolff]

i've reverted the package changes now. Thanks!

[stephendwolff]

@danielsogl there are some constants in the phonegap plugin which should be included in the ionic-native plugin. How should they be declared / annotated?

  /**
   * Android NfcAdapter.enableReaderMode flags
   */
//  let FLAG_READER_NFC_A: number = 0x1;
//  const FLAG_READER_NFC_B: 0x2,
//  const FLAG_READER_NFC_F: 0x4,
//  const FLAG_READER_NFC_V: 0x8,
//  const FLAG_READER_NFC_BARCODE: 0x10,
//  const FLAG_READER_SKIP_NDEF_CHECK: 0x80,
//  const FLAG_READER_NO_PLATFORM_SOUNDS: 0x100,

[sfaizanh]

@stephendwolff add this after https://github.com/ionic-team/ionic-native/blob/05dc6f7f0c51e5af9ec1e1b90448eed20bcc5571/src/%40ionic-native/plugins/nfc/index.ts#L78

  FLAG_READER = {
    NFC_A: 0,
    NFC_B: 0x2,
    NFC_F: 0x4,
    NFC_V: 0x8,
    NFC_BARCODE: 0x10,
    SKIP_NDEF_CHECK: 0x80,
    NO_PLATFORM_SOUNDS: 0x100,
  };