Refactor: convert_hf_to_gguf.py (#17114)

* move conversion code to a dedicated conversion directory and split the files akin to the src/models architecture

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

conversion/starcoder.py

@@ -0,0 +1,23 @@
+from __future__ import annotations
+
+from .base import ModelBase, TextModel, gguf
+
+
+@ModelBase.register("GPTBigCodeForCausalLM")
+class StarCoderModel(TextModel):
+    model_arch = gguf.MODEL_ARCH.STARCODER
+
+    def set_gguf_parameters(self):
+        self.gguf_writer.add_context_length(self.hparams["n_positions"])
+        self.gguf_writer.add_embedding_length(self.hparams["n_embd"])
+        self.gguf_writer.add_feed_forward_length(4 * self.hparams["n_embd"])
+        self.gguf_writer.add_block_count(self.block_count)
+        self.gguf_writer.add_head_count(self.hparams["n_head"])
+        self.gguf_writer.add_head_count_kv(1)
+        self.gguf_writer.add_layer_norm_eps(self.hparams["layer_norm_epsilon"])
+        self.gguf_writer.add_file_type(self.ftype)
+
+
+@ModelBase.register("Starcoder2ForCausalLM")
+class StarCoder2Model(TextModel):
+    model_arch = gguf.MODEL_ARCH.STARCODER2