Add new filename_parser entry for nirspec files

[stscijgbot-jwql]

Issue JWQL-289 was created on JIRA by Bryan Hilbert:

Looks like we missed adding the option to parse filenames such as:

jw05232-o002_t001-s000000001_nirspec_f290lp-g395m-s200a1_s2d.fits

to the list of level 3 files. We already parse e.g. jw05232-o002_s000000001_nirspec_f290lp-g395m-s200a1_s2d.fits so this should be an easy fix.