feat(util): add macro for exposing the type std::pair<T1, T2> in Lua

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

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

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