Set the deprecated tag to compiler.warn.has.been.deprecated

Author: nya3jp

src/main/java/org/javacs/lsp/DiagnosticTag.java

@@ -2,4 +2,5 @@
 
 public class DiagnosticTag {
     public static final int Unnecessary = 1;
+    public static final int Deprecated = 2;
 }

src/main/java/org/javacs/markup/ErrorProvider.java

@@ -86,6 +86,9 @@ private org.javacs.lsp.Diagnostic lspDiagnostic(javax.tools.Diagnostic<? extends
         result.message = message;
         result.range =
                 new Range(new Position(startLine - 1, startColumn - 1), new Position(endLine - 1, endColumn - 1));
+        if (code.equals("compiler.warn.has.been.deprecated")) {
+            result.tags = List.of(DiagnosticTag.Deprecated);
+        }
         return result;
     }