feat(library/kernel_bindings): add sugar for level expressions in the Lua API

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
refactor(kernel/inductive): simplify inductive datatype API

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
test(lua): add inductive datatype simple tests

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>