Support all HF models

[neverix]

This PR removes checks for the model list and changes the config format.

[norabelrose]

I fixed some unbound variable errors. Also I couldn't help myself and went ahead and fixed #25 because it was annoying me.

[lauritowal]

For Deberta I get the following error:

Traceback (most recent call last):
  File "/usr/lib/python3.9/runpy.py", line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.9/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/home/wombat_share/laurito/elk/elk/generation_main.py", line 55, in <module>
    create_hiddenstates(model, tokenizer, name_to_dataframe, args)
  File "/home/wombat_share/laurito/elk/elk/utils_generation/generation.py", line 108, in create_hiddenstates
    hidden_states = calculate_hidden_state(
  File "/home/wombat_share/laurito/elk/elk/utils_generation/generation.py", line 28, in calculate_hidden_state
    assert (
AssertionError: BERT does not have decoder. Relevant args: model=microsoft/deberta-v2-xxlarge-mnli, states_location=decoder.

@neverix