AttributeError: module 'nemo.collections' has no attribute 'nlp'
**Describe the bug**

When I try "from nemo.collections import nlp" I get the error below

```
[NeMo W 2021-11-26 06:12:43 optimizers:50] Apex was not found. Using the lamb or fused_adam optimizer will error out.
[NeMo W 2021-11-26 06:12:49 experimental:28] Module nemo.collections.nlp.data.text_normalization.decoder_dataset.TextNormalizationDecoderDataset is experimental, not ready for production and is not fully supported. Use at your own risk.
[NeMo W 2021-11-26 06:12:49 experimental:28] Module nemo.collections.nlp.data.text_normalization.tagger_dataset.TextNormalizationTaggerDataset is experimental, not ready for production and is not fully supported. Use at your own risk.
[NeMo W 2021-11-26 06:12:49 experimental:28] Module <class 'nemo.collections.nlp.data.text_normalization.test_dataset.TextNormalizationTestDataset'> is experimental, not ready for production and is not fully supported. Use at your own risk.
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-19-80f2adc350a5> in <module>
----> 1 from nemo.collections import nlp

~/anaconda3/envs/pytorch_latest_p36/lib/python3.6/site-packages/nemo/collections/nlp/__init__.py in <module>
     13 # limitations under the License.
     14 
---> 15 from nemo.collections.nlp import data, losses, models, modules
     16 from nemo.package_info import __version__
     17 

~/anaconda3/envs/pytorch_latest_p36/lib/python3.6/site-packages/nemo/collections/nlp/models/__init__.py in <module>
     14 
     15 from nemo.collections.nlp.models.dialogue_state_tracking.sgdqa_model import SGDQAModel
---> 16 from nemo.collections.nlp.models.duplex_text_normalization import (
     17     DuplexDecoderModel,
     18     DuplexTaggerModel,

~/anaconda3/envs/pytorch_latest_p36/lib/python3.6/site-packages/nemo/collections/nlp/models/duplex_text_normalization/__init__.py in <module>
     13 # limitations under the License.
     14 
---> 15 from nemo.collections.nlp.models.duplex_text_normalization.duplex_decoder import DuplexDecoderModel
     16 from nemo.collections.nlp.models.duplex_text_normalization.duplex_tagger import DuplexTaggerModel
     17 from nemo.collections.nlp.models.duplex_text_normalization.duplex_tn import DuplexTextNormalizationModel

~/anaconda3/envs/pytorch_latest_p36/lib/python3.6/site-packages/nemo/collections/nlp/models/duplex_text_normalization/duplex_decoder.py in <module>
     24 from transformers import AutoModelForSeq2SeqLM, AutoTokenizer, DataCollatorForSeq2Seq
     25 
---> 26 import nemo.collections.nlp.data.text_normalization.constants as constants
     27 from nemo.collections.common.tokenizers.moses_tokenizers import MosesProcessor
     28 from nemo.collections.nlp.data.text_normalization import TextNormalizationTestDataset

AttributeError: module 'nemo.collections' has no attribute 'nlp'
```

**Steps/Code to reproduce bug**

Install nemo (as per below), and then run the import statement above. 
Nemo version is 1.5.0. 

**Expected behavior**

I expected to the import statement to run normally. 

**Environment overview (please complete the following information)**

 - Environment location: AWS sagemaker notebook instance (m5.xlarge)
 - Method of NeMo install: 
```
conda install -c conda-forge libsndfile ffmpeg -y
pip install nemo_toolkit['all']

Note: nemo_tookit==1.5.0 was installed
```

**Environment details**

- OS version - Amazon Linux AMI release 2018.03
- PyTorch version - 1.7.1
- Python version - 3.6.13

