Tuple syntax in `IntoSystemSetConfigs::after` and co. not working

## Bevy version
0.11

## What you did

Try writing `SystemSetA.after((SystemSetB, SystemSetC))`.

## What went wrong

```rust
error[E0277]: the trait bound `(SystemSetB, SystemSetC): IntoSystemSet<_>` is not satisfied
```

The current impls of `IntoSystemSetConfigs` do not support that syntax, although it should.

Start at IntoSystemSetConfigs::after and inspect the current IntoSystemSetConfigs implementations for tuple support. Reproduce the shown SystemSetA.after((SystemSetB, SystemSetC)) example, then add coverage that verifies tuple syntax works alongside the existing forms and run the relevant test suite.

Written by the indexing model from the issue text.