Blob support causes OOM on Android with large files

@satya164 Created this issue to ask your advise regarding an OutOfMemory Error with the RN Blob support.

Following the test code in this repo. I'm attempting to create a blob from a file url. (A 400 MB HD video)

```
const response = await fetch(uri);
const blob = await response.blob();
```

While it works on iOS. On Android the fetch fails.

```
Failed to send url request: file:////data/user/0/com.package.name/cache/rn_image_picker_lib_temp_b4276c3a-82e8-4be7-b2a9-be1470358ae7.mp4
java.lang.OutOfMemoryError: Failed to allocate a 33554448 byte allocation with 19742688 free bytes and 18MB until OOM, target footprint 536870912, growth limit 536870912
at java.util.Arrays.copyOf(Arrays.java:3585)
at java.io.ByteArrayOutputStream.grow(ByteArrayOutputStream.java:120)
at java.io.ByteArrayOutputStream.ensureCapacity(ByteArrayOutputStream.java:95)
at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:156)
at com.facebook.react.modules.blob.BlobModule.getBytesFromUri(BlobModule.java:231)
at com.facebook.react.modules.blob.BlobModule.-$$Nest$mgetBytesFromUri(Unknown Source:0)
at com.facebook.react.modules.blob.BlobModule$2.fetch(BlobModule.java:83)
at com.facebook.react.modules.network.NetworkingModule.sendRequestInternal(NetworkingModule.java:278)
at com.facebook.react.modules.network.NetworkingModule.sendRequest(NetworkingModule.java:241)
at java.lang.reflect.Method.invoke(Native Method)
```

I have android:largeHeap="true" set in the Manifest and it works fine with smaller files.

Do you think this can be handled differently, i.e. not read the whole file into memory ? I'm happy to work on it if you have suggestions for better handling in either the BlobModule or js side.