flatpak-builtins-list: add `bytes` option to show installed size in bytes if the column is present

[vgdaut]

Related to the issue about GNU sort compatibility

GNU sort accepts human readable sizes in single letter "2K 1G" format. GLib's format_size() uses another format of size units "kB, MB, GB". There are format_size_full() flags, but nothing is relevant to the problem. The easiest solution is to use bytes when sorting is needed.

[swick]

LGTM