model: M3: Move MSA into a new memory implementation (#26338)

* Move MSA logic from llama-kv-cache into llama-kv-cache-msa

* cont : minor

* cont : ws fix

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

src/llama-hparams.h

@@ -230,8 +230,6 @@ struct llama_hparams {
     // MSA
     uint32_t indexer_block_size  = 0;
     uint32_t indexer_local_blocks = 0;
-    // MSA stores its indexer keys in the main KV cache (k_idx tensors);
-    bool indexer_kv = false;
 
     // Indexer is "full" (1) or "shared" (0)
     // Shared indexers reuse top-k from previous full layer
@@ -356,9 +354,6 @@ struct llama_hparams {
     uint32_t n_embd_k_gqa_max() const;
     uint32_t n_embd_v_gqa_max() const;
 
-    // dimension of the single-head MSA indexer key stream
-    uint32_t n_embd_k_idx(uint32_t il = 0) const;
-
     // dimension of the rolling state embeddings
     // corresponds to Mamba's conv_states size or RWKV's token_shift states size
     uint32_t n_embd_r() const;