Scripts can't start until lighttable mode is active

[wpferguson]

darktable-org/darktable#5959 fixed a darktable hanging issue by delaying scripts startup until the GUI entered lighttable.

Scripts that don't have a UI should be safe to start.

Scripts that do have a UI may be safe to start so that shortcut functionality is available without the UI being created until in lighttable mode.

Discussion: https://discuss.pixls.us/t/minor-problem-with-lua-scripts-only-loading-if-darktable-opens-lighttable-view/