ggml webgpu: add support for soft_max, optimize rms_norm (#16357)

* Add inplace softmax

* Move rms_norm to split row approach

* Update debug for supports_op

* clean up debug statements

* Update tests/test-backend-ops.cpp

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

---------

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

Author: reeselevine

ggml/include/ggml.h

@@ -1630,6 +1630,13 @@ extern "C" {
             float                 scale,
             float                 max_bias);
 
+    GGML_API struct ggml_tensor * ggml_soft_max_ext_inplace(
+            struct ggml_context * ctx,
+            struct ggml_tensor  * a,
+            struct ggml_tensor  * mask,
+            float                 scale,
+            float                 max_bias);
+
     GGML_API void ggml_soft_max_add_sinks(
             struct ggml_tensor * a,
             struct ggml_tensor * sinks);