Running `edgedb instance <subcommand>` in a project

[vjjft]

When working in a project, it would be useful to have an easy way to accomplish edgedb instance <subcommand> -I <project_instance_name>.

I propose having edgedb instance <subcommand> implicitly use the instance from the project, since that: aligns with the behavior of running edgedb; should not result in unexpected behavior for any of the instance subcommands; is likely the most commonly expected behavior.

[raddevon]

What do you think about this suggestion, @tailhook?

[tailhook]

This was a part of plan of deprecating edgedb instance <subcommand> <instance_name> and introducing -I. I'm not sure if deprecation period is enough, though.