feat(kernel/level): add is_geq predicate, we need it for implementing the inductive datatype validation

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(library/kernel_bindings): improve universe level Lua API

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
test(lua): add is_geq (for universe level) tests

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(library/kernel_bindings): style

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(kernel/inductive): add datatype and introduction rules declarations to environment, and fix tests

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(kernel/inductive): add more inductive datatype validation

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