This PR introduces a new feature that allows users to specify which
inductive datatypes the `grind` tactic should perform case splits on.
The configuration option `splitIndPred` is now set to `false` by
default. The attribute `[grind cases]` is used to mark inductive
datatypes and predicates that `grind` may case split on during the
search. Additionally, the attribute `[grind cases eager]` can be used to
mark datatypes and predicates for case splitting both during
pre-processing and the search.
Users can also write `grind [HasType]` or `grind [cases HasType]` to
instruct `grind` to perform case splitting on the inductive predicate
`HasType` in a specific instance. Similarly, `grind [-Or]` can be used
to instruct `grind` not to case split on disjunctions.
Co-authored-by: Leonardo de Moura <leodemoura@amazon.com>
