lalinference_pipe.py: pick the best roq bin when multiple bins are available
When a trigger chirp mass is in multiple ROQ bins, previous lalinference_pipe selects the first bin it finds. However, if the trigger chirp mass is very close to the edge of that bin, the posterior samples might rail against the edge of the bin. Instead, it should selects the best bin which provides the widest margin for the trigger chirp mass. This patch enables it.