Feature
Add support for creating symbolic links and hard links. As far as I know these concepts are supported on Android, macOS, and iOS (and Windows if it was a supported platform in future).

Motivation
These are fairly standard/common file-related functions so it makes sense for them to be part of this file-access package rather than a separate package.

There's some prior art here but (1) was never merged into react-native-fs and (2) only supports iOS:

1. https://github.com/itinance/react-native-fs/pull/859/files
2. https://github.com/vorlovsky/react-native-file-link

Details

• It should be possible to create soft and hard links (via a new ln method taking target: string, path: string, symbolic: boolean params)
• It should be possible to delete links (probably already supported by unlink?)

Open to me and/or a colleague attempting to implement this if it sounds like something you'd be happy to review @alpha0010?