Fix GraceDB coinc.xml upload with PSD

This merge includes two main features.

Firstly, it nests each LIGO_LW PSD element in the coinc.xml inside a LIGO_LW element container with the Name "PSD", to match the schema from PyCBC. This change appears to have enabled GraceDB to accept our coinc.xml uploads. For example, see the coinc.xml file inside Links --> Data in the following link: https://gracedb-playground.ligo.org/events/T480346/view/ [Direct link to coinc.xml].

The second is the inclusion of an input argument "append_psd_to_coincs_doc" to the gstlal_inspiral_postcohspiir_online bin script so that this functionality can be turned off and on without editing and re-installing the pipeline.

Additionally, there are also two datetime.now() calls that are used to estimate the total number of seconds for the GraceDB upload, and this information is printed to sys.stderr alongside the pre-existing GraceDB debug messages.