Ensure info() implementation across all SolverBase derived types

Reference issue

#2451 (closed)

What does this implement/fix?

This MR ensures that all classes inheriting SolverBase have the info() method. On the SolverBase forwarding call, I left a comment specifying that a derived class that does not implement info() will trigger infinite recursion (detectable by the compiler, though).

We could also go for @cantonios solution (see #2451 (closed)). I start by proposing the simpler one.