PoolOptions<DB> can't be cloned

[Redrield]

Bug Description

Despite the #[derive(Clone)] on PoolOptions in sqlx-core, PoolOptions cannot be cloned due to unsatisfied trait bounds on the database and database connection types.

error[E0599]: the method `clone` exists for struct `PoolOptions<Postgres>`, but its trait bounds were not satisfied
   --> src\lib.rs:106:16
    |
106 |     final_opts.clone();
    |                ^^^^^ method cannot be called on `PoolOptions<Postgres>` due to unsatisfied trait bounds
    |
   ::: C:\Users\KaitlynKenwell\.cargo\registry\src\index.crates.io-6f17d22bba15001f\sqlx-core-0.6.3\src\postgres\database.rs:11:1
    |
11  | pub struct Postgres;
    | ------------------- doesn't satisfy `Postgres: Clone`
    |
   ::: C:\Users\KaitlynKenwell\.cargo\registry\src\index.crates.io-6f17d22bba15001f\sqlx-core-0.6.3\src\pool\options.rs:45:1
    |
45  | pub struct PoolOptions<DB: Database> {
    | ------------------------------------ doesn't satisfy `PoolOptions<Postgres>: Clone`
    |
   ::: C:\Users\KaitlynKenwell\.cargo\registry\src\index.crates.io-6f17d22bba15001f\sqlx-core-0.6.3\src\postgres\connection\mod.rs:31:1
    |
31  | pub struct PgConnection {
    | ----------------------- doesn't satisfy `PgConnection: Clone`
    |
    = note: the following trait bounds were not satisfied:
            `Postgres: Clone`
            which is required by `PoolOptions<Postgres>: Clone`
            `PgConnection: Clone`
            which is required by `PoolOptions<Postgres>: Clone`

Minimal Reproduction

let opts = PgPoolOptions::default();
let opts2 = opts.clone(); // E0599

Info

• SQLx version: 0.6.3
• SQLx features enabled: time,uuid,postgres,runtime-tokio-rustls
• Database server and version: n/a
• Operating system: Windows 11
• rustc --version:

❯ rustc -vV    
rustc 1.70.0 (90c541806 2023-05-31)
binary: rustc
commit-hash: 90c541806f23a127002de5b4038be731ba1458ca
commit-date: 2023-05-31
host: x86_64-pc-windows-msvc
release: 1.70.0
LLVM version: 16.0.2

[alilleybrinker]

I believe, looking through the source, that clone should be able to be implemented manually, as the DB parameter type itself isn't stored (so the clonability of it doesn't actually matter, although the derive thinks it does). The DB parameter is used to parameterize any parent pool, and to provide the connection type used in the relevant stored function pointers.

[abonander]

Closed by #2553