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.

Fix 'Illegal Callback Invocation' Android exception

fix progress and uploadProgress not callback in iOS