AddBootModuleSymlinksToContainer: Fix symlink target

The symlink was only correct, if the container was a package. For
containers with a non-empty path to the system directory the link would
duplicate the system directory path.
FloppyBootImage: Add packagefs
boot tarfs: Support resolving "." and ".." directory entries

This makes resolving the boot module symlinks work.
VFS boot: Mount packagefs when booting off an image

... and the mounted boot volume looks like a PM Haiku. This gets the CD
boot going.
Move stuff from HaikuImageCommon to new rule

... AddPackagesAndRepositoryVariablesToContainerScript.
HaikuCD: Support package resolution