feat: Adding get_all() utility function on streaming paginator

[phayes]

Summary

This adds a get_all() utility function on the streaming / async paginator, bringing the async version up to same level as the blocking version in terms of ergonomics.

For example

// Blocking (already exists)
let all_customers = Customer::list(&client, &params).unwrap().paginate(params).get_all(&client).unwrap()

// Async (this PR)
let all_customers = Customer::list(&client, &params).await.unwrap().paginate(params).get_all(&client).await.unwrap()

Checklist

• ran cargo make fmt
• using conventional commits to hightlight user-facing fixes and features

[phayes]

It looks like a bunch of tests are failing that are unrelated to the changes in this PR - not sure what to do here

[phayes]

Also, let me know if you want me to make a sibling PR to the next branch