ggml-webgpu: FlashAttention refactor + standardize quantization support (#23834)

* Start work on flash_attn refactor

* Refactor

* Split k/v quantization

* Refactor and abstract quantization logic for flash_attn and mul_mat

* Add quantization support to tile path

* formatting

* Move to functions, add a check

ggml/src/ggml-webgpu/CMakeLists.txt

@@ -10,8 +10,11 @@ file(MAKE_DIRECTORY ${SHADER_OUTPUT_DIR})
 
 message(STATUS "Shader output dir: ${SHADER_OUTPUT_DIR}")
 
-# Find all WGSL files
-file(GLOB WGSL_SHADER_FILES "${SHADER_DIR}/*.wgsl")
+# Find all WGSL sources
+file(GLOB WGSL_SHADER_FILES
+    "${SHADER_DIR}/*.wgsl"
+    "${SHADER_DIR}/*.tmpl"
+)
 
 # Generate the header using a Python script
 add_custom_command(