Allow GL_NV_mesh_shader in fragment shaders for perprimitiveNV

- Emit relevant capability/extension for use of perprimitiveNV in fragment shader
- Remove redundant checks for mesh shader qualifiers in glslang.y
- Add profile version check for use of extension GL_NV_mesh_shader
- Add a new gtest for use of perprimitiveNV in fragment shader

Test/baseResults/spv.perprimitiveNV.frag.out

@@ -0,0 +1,54 @@
+spv.perprimitiveNV.frag
+// Module Version 10000
+// Generated by (magic number): 80007
+// Id's are bound by 23
+
+                              Capability Shader
+                              Capability MeshShadingNV
+                              Extension  "SPV_NV_mesh_shader"
+               1:             ExtInstImport  "GLSL.std.450"
+                              MemoryModel Logical GLSL450
+                              EntryPoint Fragment 4  "main" 8 11 19
+                              ExecutionMode 4 OriginUpperLeft
+                              Source GLSL 460
+                              SourceExtension  "GL_NV_mesh_shader"
+                              Name 4  "main"
+                              Name 8  "g"
+                              Name 9  "B"
+                              MemberName 9(B) 0  "f"
+                              Name 11  ""
+                              Name 17  "C"
+                              MemberName 17(C) 0  "h"
+                              Name 19  ""
+                              Decorate 8(g) Location 8
+                              MemberDecorate 9(B) 0 PerPrimitiveNV
+                              Decorate 9(B) Block
+                              Decorate 11 Location 0
+                              MemberDecorate 17(C) 0 Flat
+                              MemberDecorate 17(C) 0 Centroid
+                              Decorate 17(C) Block
+                              Decorate 19 Location 4
+               2:             TypeVoid
+               3:             TypeFunction 2
+               6:             TypeFloat 32
+               7:             TypePointer Output 6(float)
+            8(g):      7(ptr) Variable Output
+            9(B):             TypeStruct 6(float)
+              10:             TypePointer Input 9(B)
+              11:     10(ptr) Variable Input
+              12:             TypeInt 32 1
+              13:     12(int) Constant 0
+              14:             TypePointer Input 6(float)
+           17(C):             TypeStruct 6(float)
+              18:             TypePointer Input 17(C)
+              19:     18(ptr) Variable Input
+         4(main):           2 Function None 3
+               5:             Label
+              15:     14(ptr) AccessChain 11 13
+              16:    6(float) Load 15
+              20:     14(ptr) AccessChain 19 13
+              21:    6(float) Load 20
+              22:    6(float) FAdd 16 21
+                              Store 8(g) 22
+                              Return
+                              FunctionEnd

Test/spv.perprimitiveNV.frag

@@ -0,0 +1,21 @@
+#version 460
+
+#extension GL_NV_mesh_shader: require
+
+layout(location=0) 
+in B {
+    perprimitiveNV float f;
+};
+
+layout(location=4) 
+in C {
+    flat centroid float h;
+};
+
+layout(location=8) 
+out float g;
+
+void main()
+{
+    g = f + h;
+}