Add input that passes options to GAP

[stertooy]

It's merely an idea/suggestion, but I think it would be useful to have the ability to pass options to GAP. In particular, the -A flag would (imho) be useful for testing if a package still works properly when loaded with the OnlyNeeded option. This would require a small change in pkg-ci-scripts/run_tests.sh as well, of course.

[james-d-mitchell]

+1 from me, this would be a useful feature. In particular, having the ability to load a workspace would be really useful. See:
semigroups/Semigroups#961
semigroups/Semigroups#960