Better support for `bytea` type

Postico currently has only limited support for `bytea` columns. Postico can display images stored in bytea columns in the sidebar, but apart from that there is no way to look at the data.

I've just discussed some ideas with @apeiros, who uses bytea columns to store textual data that may contain invalid code points. He suggested that the data should be displayed directly in the table view, in one of the following formats:
1. ascii with escape sequences, eg. `hello\x00w\xc3\xb6rld`
2. hex, eg. `0x68656c6c6f0077c3b6726c64`
3. utf-8, eg. `hello\x00wörld`

It would be nice if Postico did some auto-detection to display data in a sensible way (eg. don't try to display images as text), and also allow the user to view data in a specific way.

I'd love to hear feedback on this. Do people actually use the bytea type? And what kind of data do you store inside?

Start by reviewing the existing sidebar display for images stored in bytea columns and the table view where bytea data is currently unavailable. Compare the proposed ASCII-with-escapes, hex, and UTF-8 formats, including the request for auto-detection and user-selected viewing. Done means bytea values can be viewed in the table in sensible or explicitly selected formats without treating images as text.

Written by the indexing model from the issue text.