.vscode: Add spirv-tools-ext to include path
.vscode: Add spirv-tools-ext to include path

37f30185 added CMake rules to copy the `OpenCLDebugInfo100.h` header out of a polluted build intermediate directory and into a separate include directory.

Add this include directory to the .vscode include paths so vscode can also find it.

All of this smell should go away once https://github.com/KhronosGroup/SPIRV-Headers/issues/137 is addressed.

Bug: b/145351270
Change-Id: I1a20e6f6b507e10c90fed38dd8a94d4b3ff590f7
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/40129
Reviewed-by: Antonio Maiorano <86d87a6550afb6b07035c9743fa181900589f7e0@google.com>
Reviewed-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>
Tested-by: Ben Clayton <1f693eb7158dc33015048c09d6712f74dabddf79@google.com>
Kokoro-Presubmit: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader