Bug 1039245 - [NFC] Move NDEF record payload parsing from NfcManager and expose it to app developers, r=gweng

`NfcUtils.fromUTF8` returns `Uint8Array`, which isn't an `Array` and doesn't have `Array.prototype` methods. This is from the original code, seems a bit hacky but the tests are passing. I checked this in regular nightly console and there it does not work. I'll switch this to something more readable.