Enable xattr for Winfsp

[infeo]

Due to #86, we had to deactivate extended attributes for Windows. It is desirable to activate again, but it depends on winfsp/winfsp#531.

[infeo]

We could do a similar approach as for getxattr:

fuse-nio-adapter/src/main/java/org/cryptomator/frontend/fuse/ReadOnlyAdapter.java

Lines 242 to 247 in 4dbe693

	if (xattr.list().stream().noneMatch(key -> key.equals(name))) {
	return switch (OS.current()) {
	case MAC -> -errno.enoattr();
	default -> -errno.enodata();
	};
	}

[infeo]

A different approach: Precheck the underlying filesystem for userdefined attribute view via FilesystemProvider::supportedAttributeViews and adjust the set of supported operations accordingly!

We would loose flexibility, if the underlying filesystem suddenly activates the userDefinedAttributeView.