text: Title: Impossible to initialize Japanese pipeline with NER model
  Body: **Describe the bug**
  Cannot instantiate Japanese pipeline with NER model.
  
  Throws the following KeyError exception:
  ```
  Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    File "/root/miniconda3/envs/stanza-test/lib/python3.8/site-packages/stanza/pipeline/core.py", line 111, in __init__
      self.processors[processor_name] = NAME_TO_PROCESSOR_CLASS[processor_name](config=curr_processor_config,
    File "/root/miniconda3/envs/stanza-test/lib/python3.8/site-packages/stanza/pipeline/processor.py", line 146, in __init__
      self._set_up_model(config, use_gpu)
    File "/root/miniconda3/envs/stanza-test/lib/python3.8/site-packages/stanza/pipeline/ner_processor.py", line 25, in _set_up_model
      args = {'charlm_forward_file': config['forward_charlm_path'], 'charlm_backward_file': config['backward_charlm_path']}
  KeyError: 'forward_charlm_path'
  ```
  
  **To Reproduce**
  ```python
  import stanza
  stanza.Pipeline('ja', processors='tokenize,ner', use_gpu=False)
  ```
  
  **Environment (please complete the following information):**
   - OS: Ubuntu 20.04
   - Python version: 3.8.5
   - Stanza version: 1.1.1
  