[FEA]: Add presets that just build per-project examples.

### Is this a duplicate?

- [X] I confirmed there appear to be no [duplicate issues](https://github.com/NVIDIA/cccl/issues) for this request and that I agree to the [Code of Conduct](CODE_OF_CONDUCT.md)

### Area

General CCCL

### Is your feature request related to a problem? Please describe.

Users/developers may wish to just build the examples for the various projects. We can simplify this process by adding presets and documenting this in the relevant READMEs.

### Describe the solution you'd like

Add configure, build, and test presets:

```
cccl-examples
libcudacxx-examples
thrust-examples
cub-examples
```

### Describe alternatives you've considered

_No response_

### Additional context

_No response_