Preserve query on timeout

[danp]

If a query hits the timeout it shows a message like:

SQL query took too long. The time limit is controlled by the sql_time_limit_ms configuration option.

But the query is lost. Hitting the browser back button shows the query before the one that errored.

It would be nice if the query that errored was preserved for more tweaking. This would make it similar to how "invalid syntax" works since #1346 / #619.

[simonw]

This is a good idea.

[simonw]

Implementing it like this, so at least you can copy and paste the SQL query back out again:

I'm not doing a full textarea because this error can be raised in multiple places, including on the table page itself. It's not just an error associated with the manual query page.

[simonw]

Demo: https://latest.datasette.io/_memory?sql=with+recursive+counter(x)+as+(%0D%0A++select+0%0D%0A++++union%0D%0A++select+x+%2B+1+from+counter%0D%0A)%2C%0D%0Ablah+as+(select+*+from+counter+limit+5000000)%0D%0Aselect+count(*)+from+blah