Hplsql.g4 - 'from_clause' parses the keyword `JOIN` into 'from_alias_clause' in 'from_table_clause' when parsing 'from_join_clause'

'from_clause' parses the keyword `JOIN` into 'from_alias_clause' in 'from_table_clause' when parsing 'from_join_clause'.

example:

Parse sql SELECT `k1, v1, k2, v2 FROM a JOIN b ON k1 = k2;`.

Now grammar will parse `JOIN` as a `from_alias_clause`, but it should be
a `from_join_clause`;