[bug] checksum not yet fixed for scoped storage

[Xavron]

Problem:

On Android 8.0 internal WinSCP "checksum sha-1 file" works. On Android 13 sd card it simply says "no read permissions".

*Internal not yet tested.

*Not yet debugged or looked into.

Expected:

It should work as on Android 8.0.

Further info:

Looks like CmdHASH (which is one of the ones I didn't work on previously for scoped storage) needs scoped storage implemented. File use here is a problem because of File.canRead() since scoped storage doesn't like this use and so it won't be able to. Because of the code setup, it fails to continue past there.

Update:

Checksum is now implemented. Will soon be added to #205.

[Xavron]

Closing as pull request added commit for this 4cdd48e