Fix an issue with non "image" mime types downloading with android download manager

[iJimmyWei]

Addresses https://github.com/joltup/rn-fetch-blob/issues/214 and https://github.com/wkh237/react-native-fetch-blob/issues/606

• filePath wasn't being set for non image based mime types, causing download manager to throw an error, even though the file downloaded successfully

[namvoeh]

Can we merge this PR asap? My app got thousands of crashes because of this issue

[darron1217]

Why this is not merged yet? I couldn't understand

[Traviskn]

666