This allows the tab completion of REINDEX to handle an optional
parenthesized list of options.  This case is more complicated than
VACUUM or ANALYZE because of CONCURRENTLY and the different object types
to consider with the reindex.

Author: Justin Pryzby
Reviewed-by: Alexey Kondratov, Michael Paquier
Discussion: https://postgr.es/m/20200403182712.GR14618@telsasoft.com