Fix new syntax check for LEFT JOIN on nested field and metadata field

[dai-chen]

Currently ON clause is required for all OUTER JOIN. However it's supposed to be missing in the case of LEFT JOIN on nested field. Need to figure out if we can handle this in grammar file. Otherwise, we have to make ON clause optional and verify in semantic analyzer.

[dai-chen]

I found another missing cases which new ANTLR parser should pass the syntax check for it. In #192, user should be able to use metadata field (mostly generated by log shipper like logstash), need to modify the grammar for this case too.

[dai-chen]

For LEFT JOIN issue, I was thinking rely on DOT ID (to decide if ON should be required or not in grammar. But it seems more complicated than I thought like this case: FROM index LEFT JOIN e.projects p, e.comments c. So I think I'd better make our grammar straightforward and add more check in upcoming semantic analyzer.