Always show DebugValue in SPIR-V disassembly. Closes #2823

* These were previously hidden by default since they generate a fair amount of
  noise in the disassembly which is not neccessarily directly useful.
* The problem is that DebugValues are steppable and so will generate an
  instruction in the debugging, but without a disassembly line you can have two
  different 'instructions' on the same disassembly line but with different
  source lines:
   > DebugLine 100
   > DebugValue ...
   > DebugLine 101
   > OpSomething ...
   In this case the DebugValue and OpSomething will both have the same disassembly line, but different source lines. This means it is impossible to reliably place a disassembly breakpoint and know which instruction to stop on, and produces some odd effects when stepping in asm (it will step to the DebugValue then the OpSomething and not visibly move).
* Overall the reduction in readability is worth this fix, especially considering
  that when debug info is present is exactly when people are least likely to be
  using the disassembly at all.

renderdoc/driver/shaders/spirv/spirv_disassemble.cpp

@@ -28,9 +28,6 @@
 #include "spirv_op_helpers.h"
 #include "spirv_reflect.h"
 
-RDOC_CONFIG(bool, Vulkan_Debug_ShowDebugValues, false,
-            "Show DebugValue instructions in shader disassembly.");
-
 struct StructuredCFG
 {
   enum
@@ -1603,15 +1600,15 @@ rdcstr Reflector::Disassemble(const rdcstr &entryPoint,
 
               ret += ")";
             }
-            else if(dbg.inst == ShaderDbg::Value && Vulkan_Debug_ShowDebugValues())
+            else if(dbg.inst == ShaderDbg::Value)
             {
               OpShaderDbg localVar(GetID(dbg.arg<Id>(0)));
               ret += indent;
               ret += "// DebugValue(";
               ret += idName(dbg.arg<Id>(1));
-              ret += " = ";
+              ret += " is ";
               ret += idName(localVar.arg<Id>(0));
-              ret += " ";
+              ret += " @ ";
               ret += idName(localVar.arg<Id>(2));
               ret += ":";
               ret += idName(localVar.arg<Id>(3));