Use DefaultAzureCredential by default for Azure paths

Some libraries, such as `polars` and `pandas`, have an almost seamless method for interacting with cloud storage paths.

e.g.:

``` python
import polars as pl
pl.scan_csv('az://container/path/to/file.csv', storage_options={'account_name': 'mystorageaccount'}).collect()
```

This is nice, because I don't need to import any other libraries, setup credentials or blob clients, etc.
It automatically finds any available credentials in my local environment, presumably with something like `DefaultAzureCredential`.
This means that when testing locally, I just need to be authenticated with Azure CLI, and everything just works.
I don't even need to manually specify environment variables.
It also means that I can deploy the same code to the server, and it will automatically find the appropriate environment variables to authenticate as a service principal with `AZURE_CLIENT_ID`, `AZURE_CLIENT_SECRET`, etc.

I may have missed something, but it seems that `cloudpathlib` has not enabled this kind of automatic credential detection with `DefaultAzureCredential`. Instead, I need to do the following to get an authenticated working `CloudPath`:

``` python
from azure.identity import DefaultAzureCredential
from cloudpathlib import CloudPath, AzureBlobClient

credential = DefaultAzureCredential()
client = AzureBlobClient(account_url="https://mystorageaccount.blob.core.windows.net", credential=credential)

path = CloudPath('az://container/path/to/file.csv', client=client)
```

Ideally, it would be nice to be able to do the setup automatically.
I'm imagining the following future state:

``` python
from cloudpathlib import CloudPath
path = CloudPath('az://container/path/to/file.csv', storage_options={'account_name': 'mystorageaccount'})
```

(There may be a nicer way to specify the account name. I'm just copying the API from `polars` and `pandas` here. I kind of wish that it was standard to include the account name in the path somehow, as passing the account name in separately feels clunky to me. It would be nice if we could use `az://mystorageaccount/container/...`)

See the documentation for `DefaultAzureCredential`. (There's a reason it's called _Default_!):

- [DefaultAzureCredential documentation](https://learn.microsoft.com/en-au/python/api/azure-identity/azure.identity.defaultazurecredential?view=azure-python)
- [Azure Storage DefaultAzureCredential examples](https://learn.microsoft.com/en-us/azure/storage/blobs/storage-quickstart-blobs-python?tabs=managed-identity%2Croles-azure-portal%2Csign-in-azure-cli&pivots=blob-storage-quickstart-scratch#authenticate-to-azure-and-authorize-access-to-blob-data)
- [Azure Identity Overview (including DefaultAzureCredential examples)](https://learn.microsoft.com/en-us/python/api/overview/azure/identity-readme?view=azure-python#authenticate-with-defaultazurecredential)

Note: If you are using `fsspec` + `adlfs`, `adlfs` requires the storage option `anon=False` to be set to enable `DefaultAzureCredential`.

For example, when using `pandas`, you must specify `storage_options={'anon': False}`.
When using `fsspec` directly, you need to pass it as follows:

``` python
fs = fsspec.filesystem('az', account_name='mystorageaccount', anon=False)
```

For more details, see:
https://github.com/fsspec/adlfs#setting-credentials