Re-enable Z3 4.5.0 for better interpolation

[leventeBajczi]

Old versions of z3 were really good at interpolation, and I want to add support for it in JavaSMT.

To this end, I've added the implementation of a Z3Legacy solver (to be renamed, as discussed with @baierd), which builds on the 4.5.0 release of z3, rebuilt to use com.microsoft.z3legacy as its package name to avoid name collisions with new z3.

Pre-built binaries with the modifications are available at https://github.com/leventeBajczi/z3/releases/tag/legacy-4.3.0-15644597379, which Theta already uses like this. This should be somehow integrated into the solver management of JavaSMT, which I have no experience with.

To demonstrate how good this version of Z3 is, I ran some preliminary tests in CPAchecker, and found that an NLA encoding of programs using Z3 as the interpolation solver in the predicate analysis configuration results in 510 successfully solved tasks, which are otherwise unsolved by the bitprecise encoding of the same tasks with mathsat5.

Also, I found that #381 (which I opened) is referenced in 3 of the tests, that now failed on this implementation. I removed the overly constraining line which expected the constraint IDs to be unique, which is not necessary IMO if the interpolation problem reported in that issue is otherwise handled - which it seems to be.