Add ConvMixer Models (#1281)

* initial

* paper

* config

* ConvMixer Layer

* Patch Embedding

* ConvMixer

* All Variants

* Update __init__

* Update __init__

* Update black

* tests

* docs fix

* apply

* fix

* fix

* fix failing tests

* Format

* minor fix

* update

* Docs Fix

Author: IMvision12

keras_cv/models/__init__.py

@@ -12,6 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from keras_cv.models.convmixer import ConvMixer_512_16
+from keras_cv.models.convmixer import ConvMixer_768_32
+from keras_cv.models.convmixer import ConvMixer_1024_16
+from keras_cv.models.convmixer import ConvMixer_1536_20
+from keras_cv.models.convmixer import ConvMixer_1536_24
 from keras_cv.models.convnext import ConvNeXtBase
 from keras_cv.models.convnext import ConvNeXtLarge
 from keras_cv.models.convnext import ConvNeXtSmall