Be more consistent with column quoting

[simonw]

This tutorial made me notice that Datasette is pretty inconsistent with how column quoting works: https://datasette.io/tutorials/learn-sql

It has examples of each of "table_name" and [table_name] and table_name, and it uses single quoted values too.

Datasette should generate SQL as consistently as possible to support learners.

That tutorial should also provide a tiny bit of extra information about what's going on here.