ggml : move rope type enum to ggml.h

This commit moves the `llama_rope_type` enum from `llama.h` to
`ggml.h` and changes its name to `ggml_rope_type`.

The motivation for this change is to address the TODO in `llama.h` and
use the enum in ggml.

Note: This commit does not change the `mode` parameter to be of type
`enum ggml_rope_type`. The name `mode` and its usage suggest that it
might be more generic and possibly used as a bit field for multiple
flags. Further investigation/discussion may be needed to determine
if `mode` should be restricted to RoPE types.

ggml/include/ggml.h

@@ -437,6 +437,14 @@ extern "C" {
         GGML_FTYPE_MOSTLY_Q4_0_8_8 = 27, // except 1d tensors
     };
 
+    // Rotary Positional Embedding (RoPE) types
+    enum ggml_rope_type {
+        GGML_ROPE_TYPE_NONE = -1,
+        GGML_ROPE_TYPE_NORM =  0,
+        GGML_ROPE_TYPE_NEOX =  2,
+        GGML_ROPE_TYPE_GLM  =  4,
+    };
+
     // available tensor operations:
     enum ggml_op {
         GGML_OP_NONE = 0,