[darwin] Add support for apfs to storage provider.

[ksooo]

before:

after:

@Memphiz good to go?

And no, I don't feel responsible to fix the "..." UI glitsch in the system info window.

Darwin "df" does not seem to provide a way to remove the "inode" information, without altering other row values non-human-readable. According to the man page, adding "-P" parameter will remove the inode information and it does. But "df -HPT ufs,cd9660,hfs,apfs,udf" produces this

Filesystem   512-blocks      Used Available Capacity  Mounted on
/dev/disk1s1  975221032 495381088 472195496    52%    /
/dev/disk1s4  975221032   6291496 472195496     2%    /private/var/vm

which is of no use for end users.

[Memphiz]

Will Check in a min of this also works on older MacOS versions that don‘t know apfs ...

[ksooo]

Will Check in a min of this also works on older MacOS versions that don‘t know apfs ...

It should as unknown fs types are ignored by "df". I tested this, but only with a nonsense type on 10.13. But yeah, can't hurt if we double check.

[Memphiz]

Fine as is - tested with El Capitan at least. thx :)