This PR depends on dask/dask#9475 (**Now Merged**)

After dask#9475, external libraries are now able to implement (and expose) their own `DataFrameBackendEntrypoint` definitions to specify custom creation functions for DataFrame collections. This PR introduces the `CudfBackendEntrypoint` class to create `dask_cudf.DataFrame` collections using the `dask.dataframe` API. By installing `dask_cudf` with this entrypoint definition in place, you get the following behavior in `dask.dataframe`:

```python
import dask.dataframe as dd
import dask

# Tell Dask that you want to create DataFrame collections
# with the "cudf" backend (for supported creation functions).
# This can also be used in a context, or set in a yaml file
dask.config.set({"dataframe.backend": "cudf"})

ddf = dd.from_dict({"a": range(10)}, npartitions=2)
type(ddf)  # dask_cudf.core.DataFrame
```

Note that the code snippet above does not require an explicit import of `cudf` or `dask_cudf`. The following creation functions will support backend dispatching after dask#9475:

- `from_dict`
- `read_paquet`
- `read_json`
- `read_orc`
- `read_csv`
- `read_hdf`

See also: dask/design-docs#1

Authors:
  - Richard (Rick) Zamora (https://github.com/rjzamora)

Approvers:
  - GALI PREM SAGAR (https://github.com/galipremsagar)

URL: #11920