Add mistral to obcq

[mgoin]

Adds mistral support for the obcq script using the latest nm-transformers. This diff experiments with loading with the simple AutoModel interface and finding the model arch name from the config file's model_type

Here is a sample recipe I used for zephyr-beta

test_stage:
  obcq_modifiers:
    QuantizationModifier:
      ignore:
        - MistralRotaryEmbedding
        - MistralRMSNorm
        - SiLUActivation
        - model.layers.1.mlp.down_proj
        - model.layers.31.mlp.down_proj
        - model.layers.30.mlp.down_proj
        - model.layers.30.mlp.gate_proj
        - model.layers.30.mlp.up_proj
      post_oneshot_calibration: True
      scheme_overrides:
        Embedding:
          input_activations: null
          weights:
            num_bits: 8
            symmetric: False
    SparseGPTModifier:
      sparsity: 0.5
      block_size: 128
      sequential_update: False
      quantize: True
      percdamp: 0.01
      prunen: 0
      prunem: 0
      targets: [
        "model.layers.0",
        "model.layers.1",
        "model.layers.2",
        "model.layers.3",
        "model.layers.4",
        "model.layers.5",
        "model.layers.6",
        "model.layers.7",
        "model.layers.8",
        "model.layers.9",
        "model.layers.10",
        "model.layers.11",
        "model.layers.12",
        "model.layers.13",
        "model.layers.14",
        "model.layers.15",
        "model.layers.16",
        "model.layers.17",
        "model.layers.18",
        "model.layers.19",
        "model.layers.20",
        "model.layers.21",
        "model.layers.22",
        "model.layers.23",
        "model.layers.24",
        "model.layers.25",
        "model.layers.26",
        "model.layers.27",
        "model.layers.28",
        "model.layers.29",
        "model.layers.30",
        "model.layers.31",
      ]
      target_ids: ["attention_mask", "position_ids"]