chore(*): remove Lua 'migrate'

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

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

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean/notation_cmd): improve 'notation' cmd

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean/notation_cmd): improve 'notation' cmd