lua scripts installer does not start

[wpferguson]

Describe the bug
When darktable 3.2.x is started it should display the lua scripts installer module if the lua scripts are not installed, but it does not.

To Reproduce

1. Ensure lua scripts are not installed.
2. Start darktable 3.2.x
3. No lua scripts installer module appears in the lower left panel

Expected behavior
lua scripts installer should be present

Platform (please complete the following information):

• Darktable Version: 3.2.x+
• OS: all

Additional context
When I did PR #5857 I checked to ensure I fixed #5840. I did not check to see if I introduced a regression. I misread the API and ended up coding a test that would never pass, so the lua scripts installer will not start. As it turns out, this may have been a fortunate error. While troubleshooting this problem I discovered #5884. If a lot of people had installed the scripts and had any action that would have started darktable in darkroom mode (i.e. front end to gimp, double click in file manager, etc.) then darktable would have hung on start.

#5884 must be fixed before this is fixed. I will also feel more comfortable after trying this in a couple of release candidates, especially on windows.

[wpferguson]

#5884 is fixed by lua scripts PR 279.