Fix WGPU test by provding TEST_INPUT for outputBuffer (shader-slang#5611)

This makes tests/bugs/shadowed-lookup.slang pass on WGPU.
The underlying issue seems similar to shader-slang#5277.

Author: aleino-nv

tests/bugs/shadowed-lookup.slang

@@ -1,6 +1,6 @@
 //TEST:COMPARE_COMPUTE_EX: -slang -compute
-//DISABLE_TEST(compute):COMPARE_COMPUTE_EX:-wgpu
 
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
 RWStructuredBuffer<float> outputBuffer;
 
 struct SomeType

tests/expected-failure-github.txt

@@ -13,7 +13,6 @@ tests/bugs/frexp-double.slang.7 syn (wgpu)
 tests/bugs/gh-3980.slang.7 syn (wgpu)
 tests/bugs/gh-518.slang.2 syn (wgpu)
 tests/bugs/op-assignment-unify-mat.slang.4 syn (wgpu)
-tests/bugs/shadowed-lookup.slang.1 syn (wgpu)
 tests/bugs/user-attribute-lookup.slang.2 syn (wgpu)
 tests/compute/atomics (wgpu)
 tests/compute/atomics-buffer (wgpu)