Add file size to `-l` flag to ls

[d0sboots]

Someone was having savefile size issues, and eventually tracked it down to one excessively large log file. This would be much easier to figure out if ls had a way to show the sizes, like the standard commandline tool.

Since we don't have a "real" filesystem, most of the flags to ls won't ever apply, but this one does. Things like port openers and .msg files could show 0 bytes, or some other thing.

[catloversg]

For context, this idea comes from #1956.

If anybody has the same problem and we still have not implemented this feature, they can troubleshoot it by using "Diagnose files" in the Options tab.

[vladtepesch]

maybe ls -l also could show mem requirements of the files, if applicable