Enabling skygrids at the workflow level

[sebastiangomezlopez]

Even though the skygrid functionalities have been implemented inside pycbc_multi_inspiral, at the moment we can not pass skygrids as input when generating PyGRB workflows.

Unlike our initial tests on GRB170817A, where a single point in the grid is enough. We need this implementation for GRBs that are poorly resolved in the sky.

[pannarale]

I started looking at where to change the code and I realised that even generating injections will have to take into account the sky uncertainty. @sebastiangomezlopez told me that @MarcoCusinato and @Thomas-JACQUOT both brought this up on a call.

[titodalcanton]

@pannarale in my view, the sky location of injections would be handled directly by drawing the distribution for ra and dec from either fisher_sky or healpix_sky (once #4848 is merged).

[MarcoCusinato]

@pannarale, @titodalcanton brought up the idea of appending the sky type and ra and dec from the workflow to the injections. I think that probably one of the easiest ways would be to create the files needed to do the injections at a workflow levels like in here. Then use them to run the injection workflow.

[pannarale]

Note to self: we can remove ipn_file, ipn_sky_points and other related things.