feat(frontends/lean/parse_table): add typedef for notation::parse_table

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(util/trie): bug in for_each method

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean/token_set): add token_set Lua API

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