feat: Solver solutions pre/post-interaction support

[squadgazzz]

Excerpt from #2607

[fleupold]

I don't think JIT orders need to support pre-interactions per se. Instead, I think the solution that solvers return should allow them to specify pre and post interactions for the whole settlement (on top of the ones that are specified by each user order).

This would allow solvers to also invoke pre interactions without needing to specify a JIT order (not sure if there is a use case for it), but in any case any solver that is crafting a JIT order could also just attach its pre-interactions on the outer solution struct.