Generate samples for `get` operations

```rust
# use google_cloud_secret_manager_v1::client::SecretManagerService
async fn sample(client: &SecretManagerService, secret_name: &str) -> gax::Result<()> {
    let secret =  client
        .get_secret()
        .set_name(secret_name)
        .send()
        .await?;
    println!("{secret:?}");
    Ok(());
} 

```