vulkan: Add fusion support for RMS_NORM+MUL (#14366)

* vulkan: Add fusion support for RMS_NORM+MUL

- Add a use_count to ggml_tensor, so we can detect if an output is used more than once.
- Change the ggml-vulkan rms_norm shader to optionally multiply by another tensor.
- Add detection logic and basic fusion logic in ggml-vulkan.
- Add some testing support for fusion. Rather than computing one node at a time, allow
for computing the whole graph and just testing one node's results. Add rms_norm_mul tests
and enable a llama test.

* extract some common fusion logic

* fix -Winconsistent-missing-override

* move ggml_can_fuse to a common function

* build fix

* C and C++ versions of can_fuse

* move use count to the graph to avoid data races and double increments when used in multiple threads

* use hash table lookup to find node index

* change use_counts to be indexed by hash table slot

* minimize hash lookups

style fixes

* last node doesn't need single use.
fix type.
handle mul operands being swapped.

* remove redundant parameter

---------

Co-authored-by: slaren <slarengh@gmail.com>

ggml/src/ggml-vulkan/vulkan-shaders/vulkan-shaders-gen.cpp

@@ -497,7 +497,7 @@ void process_shaders() {
     // Norms
     string_to_spv("norm_f32", "norm.comp", merge_maps(base_dict, {{"A_TYPE", "float"}, {"D_TYPE", "float"}}));
     string_to_spv("group_norm_f32", "group_norm.comp", merge_maps(base_dict, {{"A_TYPE", "float"}, {"D_TYPE", "float"}}));
-    string_to_spv("rms_norm_f32", "rms_norm.comp", merge_maps(base_dict, {{"A_TYPE", "float"}, {"D_TYPE", "float"}}));
+    string_to_spv("rms_norm_f32", "rms_norm.comp", merge_maps(base_dict, {{"A_TYPE", "float"}, {"B_TYPE", "float"}, {"D_TYPE", "float"}}));
     string_to_spv("rms_norm_back_f32", "rms_norm_back.comp", merge_maps(base_dict, {{"A_TYPE", "float"}, {"B_TYPE", "float"}, {"D_TYPE", "float"}}));
     string_to_spv("l2_norm_f32", "l2_norm.comp", merge_maps(base_dict, {{"A_TYPE", "float"}, {"D_TYPE", "float"}}));