Implement accessing a column by name for the Any driver to fix FromRow

[sciyoshi]

With the following minimal test case:

use sqlx::any::AnyConnection;

#[derive(sqlx::FromRow, Debug)]
pub struct User {
    pub id: i64,
    pub username: String,
}

impl User {
    pub async fn get_from_id(db: &mut AnyConnection, id: i64) -> Option<Self> {
        sqlx::query_as::<_, User>("SELECT * FROM users WHERE id = ? LIMIT 1")
            .bind(id)
            .fetch_one(db)
            .await
            .ok()
    }
}

I get the following compile error:

error[E0277]: the trait bound `str: sqlx_core::row::ColumnIndex<sqlx_core::any::row::AnyRow>` is not satisfied
  --> src/model.rs:34:14
   |
34 |             .fetch_one(db)
   |              ^^^^^^^^^ the trait `sqlx_core::row::ColumnIndex<sqlx_core::any::row::AnyRow>` is not implemented for `str`

According to @mehcode on Discord, the Any driver needs to implement accessing a column by name for FromRow to work.