feat(frontends/lean/builtin_cmds): add definition command family

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean/parser): allow explicit universe level to be provided to aliases and locals

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
test(lean/run): add overload test

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