Backport verify_destination from Nautilus - Symlink and freespace fixes

[rcaridade145]

Should help with the symlink issues like #315 , #947 , #748 . This version also verifies the amount of freespace available before copy.

[lukefromdc]

Note that with g_autofree only gcc and clang can build the code (see dunst-project/dunst#522) but I'm not sure we need to worry about this at all, and if this is a backport from GNOME they don't either.

[lukefromdc]

This builds and runs fine, not sure how to test the intended use cases of this. Copying a symlink still defaults to making a copy of the symlink, not the contents of the directory it points to. Most importantly, deleting a test symlink deleted the symlink and not the directory pointed to. Needs testing with the issues references but as a GNOME backport this should hopefully work here as in Nautilus.

[raveit65]

How to test?

[rcaridade145]

@raveit65 The commit I first looked into was https://gitlab.gnome.org/GNOME/nautilus/commit/f83d19ac913964240515338e8858977cf6632157 but ended up porting the latest version of the code. This commit mentions issue #947 but the code is from master. At least #947 ought to be solved by this.

[rcaridade145]

#748 is already fixed by the last backport on #1058 . Sorry for the confusion with all these backports :/

[raveit65]

I don't get why origin patch from #947 or https://bugzilla.redhat.com/show_bug.cgi?id=1554084
only edit 3 lines.
And you edit much more code.

[raveit65]

No answer from author since nealy 1 year, closing this one. We can re-open PR if someone start again to work on it.