Merge gstlal O4b online review tag.

Merges to https://git.ligo.org/lscsoft/gstlal/-/tags/o4b-online-v1.0.0, which I believe is the reviewed O4b gstlal online review tag. I'm yet to find their review page & check the commit hash.

The latest version includes some files in git LFS for testing. I've removed them as we don't require them, and I can't access some of the files regardless.

The latest version also includes a version of the changes I'd attempted in !9 (closed), though I've also noticed that one of the original tickets has been responded to, so there may be yet another workaround: https://gitlab.gnome.org/GNOME/pygobject/-/issues/488. It refers to properties directly though, so I'm not sure that it's viable for our usage.

Requires a build & tests.