AST: Quote attributes more consistently in DiagnosticsCommon.def

Author: AnthonyLatsis

include/swift/AST/DiagnosticsCommon.def

@@ -87,7 +87,7 @@ ERROR(require_literal_initializer_for_literal,none,
       "_const let should be initialized with a literal value", ())
 
 ERROR(require_const_initializer_for_const,none,
-      "@const value should be initialized with a compile-time value", ())
+      "'@const' value should be initialized with a compile-time value", ())
 
 ERROR(require_const_arg_for_parameter,none,
       "expected a compile-time value argument for a '@const' parameter", ())

test/ConstValues/DiagModules.swift

@@ -17,5 +17,5 @@ public func foo() -> Int {
 import MyModule
 
 @const let constGlobal1: Int = foo()
-// expected-error@-1 {{@const value should be initialized with a compile-time value}}
+// expected-error@-1 {{'@const' value should be initialized with a compile-time value}}
 // expected-error@-2 {{global variable must be a compile-time constant}} // Remove this once we common out the diagnostics

test/ConstValues/DiagNotConst.swift

@@ -3,13 +3,13 @@
 // RUN: %target-swift-frontend -emit-ir -primary-file %s -parse-as-library -verify -enable-experimental-feature CompileTimeValues
 
 @const let a: Bool = Bool.random()
-// expected-error@-1 {{@const value should be initialized with a compile-time value}}
+// expected-error@-1 {{'@const' value should be initialized with a compile-time value}}
 // expected-error@-2 {{global variable must be a compile-time constant}} // Remove this once we common out the diagnostics
 
 func foo() -> Int {
 	return 42 * Int.random(in: 0 ..< 10)
 }
 
 @const let b: Int = foo()
-// expected-error@-1 {{@const value should be initialized with a compile-time value}}
+// expected-error@-1 {{'@const' value should be initialized with a compile-time value}}
 // expected-error@-2 {{global variable must be a compile-time constant}} // Remove this once we common out the diagnostics