Various changes to fix Predictions category for AWS Amplify React Native

files.js

// Utils.js
// new util for RN File Source
export async function fileToRNArrayBuffer(uri) {
  return new Promise((res, reject) => {
      var request = new XMLHttpRequest();
      request.open("GET", uri, true);
      request.responseType = "arraybuffer";
      request.onload = _event => { res(request.response) }      
      request.onerror = err => { reject(err); };
      request.send(null);
  });
}

// AmazonAIIdentifyPredictionsProvider.js
// update imports
import {
    IdentifyLabelsInput, IdentifyLabelsOutput, IdentifySource, IdentifyEntitiesInput, IdentifyEntitiesOutput,
    isStorageSource, isFileSource, isRNFileSource, isBytesSource, IdentifyTextInput, IdentifyTextOutput, isIdentifyCelebrities,
    isIdentifyFromCollection, IdentifyFromCollection
  } from '../types';
import { makeCamelCase, makeCamelCaseArray, blobToArrayBuffer, fileToRNArrayBuffer } from './Utils';

// check if is RNFilesource
else if (isRNFileSource(source)) {
  fileToRNArrayBuffer(source.file.uri)
    .then(buffer => { res({ Bytes: buffer }) })
    .catch(err => rej(err))
}

// types/Predictions.js
// New types for RNFileSource
export type IdentifySource = StorageSource | FileSource | BytesSource | RNFileSource;

export function isRNFileSource(obj: any): obj is RNFileSource {
    const key: keyof RNFileSource = 'file';
    const uri: keyof RNFile = 'uri';
    return obj && obj.hasOwnProperty(key) && obj[key].hasOwnProperty(uri);
}

export interface RNFileSource {
    file: RNFile
}

export interface RNFile {
    uri: string
    width: number
    height: number
}