Infer that terms are defined to send to SMT solver

[ana-pantilie]

Fixes #2287

1. Can now declare symbols to be used when translating test data for the solver.
2. Added unit tests as described in the issue. The first two tests had to be commented out, because of this issue. The other two should have only passed after these changes, but they used to pass before as well. Changing this to empty makes all new unit tests pass, though.
3. Further changes should be described in the issue.

---

Review checklist

The author performs the actions on the checklist. The reviewer evaluates the work and checks the boxes as they are completed.

• Summary. Write a summary of the changes. Explain what you did to fix the issue, and why you did it. Present the changes in a logical order. Instead of writing a summary in the pull request, you may push a clean Git history.
• Documentation. Write documentation for new functions. Update documentation for functions that changed, or complete documentation where it is missing.
• Tests. Write unit tests for every change. Write the unit tests that were missing before the changes. Include any examples from the reported issue as integration tests.
• Clean up. The changes are already clean. Clean up anything near the changes that you noticed while working. This does not mean only spatially near the changes, but logically near: any code that interacts with the changes!

[ttuegel]

Why not move this outside SMT.withSolver instead?