Solve the conflict between FileProvider and other libraries

Androidx upgrade

fix cocoa pod 0.60.0 for rn-fetch-blob

Remove unused AsyncStorage import (Deprecated in RN 0.59)

See: https://developer.android.com/reference/java/nio/charset/Charset.html#defaultCharset()

> Android note: The Android platform default is always UTF-8.

See: https://developer.android.com/reference/java/nio/charset/Charset.html#defaultCharset()

> Android note: The Android platform default is always UTF-8.

These constants were never actually implemented.

This is caused by an error on Android 9: 'Error: Calling startActivity() from outside of an Activity  context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?'

Not working in iPhone due to presence of charset utf-8

This fixed the warning for "require cycle" on newer React-Versions

This reverts commit d69c72bb3f, reversing
changes made to c95ef1c199.

Add flow type definitions

update android build config for newer react-native versions

index.d.ts: Fix extends -> implements

Before:
```
node_modules/rn-fetch-blob/index.d.ts:147:43 - error TS2689: Cannot extend an interface 'EventTarget'. Did you mean 'implements'?

147 export declare class PolyfillBlob extends EventTarget {
                                              ~~~~~~~~~~~

error Command failed with exit code 1.
```

After:
```
✨  Done in 3.06s.
```

Add typescript type defenitions

Adding iOS background upload support

path sent to unlink is now checked for file prefix.