lot of refactoring

src/pet/task_mapping.py

@@ -0,0 +1,17 @@
+from .pet_model import PETModelForCausalLM, PETModelForSeq2SeqLM, PETModelForSequenceClassification
+from .tuners import PrefixTuningConfig, PromptEncoderConfig, PromptTuningConfig
+from .utils import PETConfig
+
+
+MODEL_TYPE_TO_PROMPT_MODEL_MAPPING = {
+    "SEQ_CLS": PETModelForSequenceClassification,
+    "SEQ_2_SEQ_LM": PETModelForSeq2SeqLM,
+    "CAUSAL_LM": PETModelForCausalLM,
+}
+
+PET_TYPE_TO_CONFIG_MAPPING = {
+    "PROMPT_TUNING": PromptTuningConfig,
+    "PREFIX_TUNING": PrefixTuningConfig,
+    "P_TUNING": PromptEncoderConfig,
+    "LORA": PETConfig,
+}