perf scripts python: exported-sql-viewer.py: Add ability to display all the database tables

Displaying all the database tables can help make the database easier to
understand.

Committer testing:

Opened all the tables, even the sqlite master table, which I selected
everything and used control+C, lets see if it works...

  CREATE VIEW threads_view AS SELECT id,machine_id,(SELECT host_or_guest FROM machines_view WHERE id = machine_id) AS host_or_guest,process_id,pid,tid FROM threads

Humm, nope, just one of the cells got copied, even with everything selected :-)

Anyway, works as advertised, useful for perusing the data.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20181001062853.28285-17-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>