SpirvShaderDebugger: Implement scope nesting
SpirvShaderDebugger: Implement scope nesting

Previously nested scopes would hide their parent variables.
This is no longer the case.

Bug: b/148401179
Change-Id: Icf2771a525524b8796ab12e295e141388bb5b399
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/42368
Kokoro-Presubmit: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>
Tested-by: Ben Clayton <1f693eb7158dc33015048c09d6712f74dabddf79@google.com>

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