Replace local tabulate formats with those available upstream

[kdeldycke]

FYI, I just proposed a new PR in the upstream python-tabulate project to add some new unicode-based table rendering.

The new renderings can now replace the formats hard-coded in cli_helpers:

• psql_unicode => simple_outline
• double => double_outline
• ascii => outline

See more details at: https://github.com/astanin/python-tabulate/pull/151

[kdeldycke]

For the record, I backported all the new formats to my own standalone package: click-extra.

[kdeldycke]

I am no longer using cli_helpers and have switched to directly depending on python-tabulate for my use-case.

I now rely exclusively on click-extra as a replacement for cli_helpers.