Add semantic highlighting for macros

Author: ahoppen

Sources/SourceKitLSP/Swift/SyntaxHighlightingTokenParser.swift

@@ -156,6 +156,10 @@ struct SyntaxHighlightingTokenParser {
       values.refFunctionPostfixOperator,
       values.refFunctionInfixOperator:
       return (.operator, [])
+    case values.declMacro:
+      return (.macro, [.declaration])
+    case values.refMacro:
+      return (.macro, [])
     case values.declVarStatic,
       values.declVarClass,
       values.declVarInstance: