RFR 8213031: (zipfs) Add support for POSIX file permissions

[Langer, Christoph]

Hi Alan,

here is the next iteration: http://cr.openjdk.java.net/~clanger/webrevs/8213031.7/

I focused on your comments regarding implementation details:

> I'm not sure about using ${user.name} and "<zipfs_default>" as default.
> Have you looked at using the zip file owner/group (or owner/owner on
> Windows) as the default?  Also just wondering if 777 might be more
> appropriate (maybe you have a reason for choosing 660?). It might be
> useful to see what Linux, macOS and other operating systems do when
> mounting a FAT file system.

I'm using Files.getOwner() now as well as the default of 777 for permissions.

> Did you consider using the string representation of the user, group and
> permissions in the configuration properties? The zip file system
> provider could support both of course. String might make it a bit easier
> to create the map of configuration properties when creating the file
> system e.g
> Map.of("enablePosixPermissions", "true", "defaultOwner", "joe",
> "defaultPermissions", "rw-rw---");

Implemented.

I also added Lance's suggestions to the test.

Are there other major implementation points left? If not I guess we should start refining the documentation...

Thanks
Christoph