query_as! implementation which uses FromRow

[0xForerunner]

Is your feature request related to a problem? Please describe.
I'd like to be able to use the static type checking we get from the query_as! macro, but I'd like it to use the FromRow implementation.

This is necessary to concisely query more complicated types who's fields don't implement Decode

Consider something simple like this:

#[derive(Clone, Eq, PartialEq, Hash, Debug, FromRow)]
pub struct MyType {
    #[sqlx(try_from = "i64")]
    pub index: usize,
    #[sqlx(flatten)]
    pub element:  TypeThatImplsFromRow,
}

This would be a PITA to use query_as! due to the limitations I mentioned above.

Describe the solution you'd like
Perhaps something like:

query_as!(MyType as FromRow, "INSERT SQL HERE")

or

query_from!(MyType, "INSERT SQL HERE")

Describe alternatives you've considered
I'm not aware of any.

[saiintbrisson]

Dup of #514. This has been widely requested for a long time now, but the current structure isn't capable of handling such change.

[0xForerunner]

Sorry about that, somehow I missed that in my search. I'll go ahead and close. Thanks! @saiintbrisson