Update location for romcpy etc output

[reticulatedpines]

Old scripting assumes run scripts are used from within the combined build and src dir, and assumes a named dir exists per cam at top-level.

We now use split build and src dirs (cleaner, and the recommended Qemu build process). We have per cam dirs under cam_config so the top-level is not as crowded.

-d romcpy and similar output files according to the old assumptions. Where should these go under the new scheme? If we use run_qemu.py from the source dir, output into that dir or lower will be git managed, so we'd have to have a good .gitignore which might be impractical. If we output outside of git managed dirs (rom dir?), we need to be clear where the output is, and would like it to work neatly with the consumers of the output files.