Additional helper methods for `query_typed`

[maxdeviant]

Since #1147 we now have query_typed, which allows using tokio-postgres with pools that do not have prepared statements.

However, there don't seem to be equivalents for query_one, query_opt, which would be useful to have.

Is this something that would we would be interested in adding? I'd be happy to open a PR for it.

[ramnivas]

I think that would be a good addition.

[maxdeviant]

I think that would be a good addition.

By the way, thank you for your blog posts on using Hyperdrive from Rust and work on query_typed 🙂