Support completions for JSDoc @param tag names (#16299)

* Support completions for JSDoc @param tag names

* Undo change to finishNode

* Don't include trailing whitespace in @param range; instead, specialize getJsDocTagAtPosition

src/services/classifier.ts

@@ -814,7 +814,7 @@ namespace ts {
          * False will mean that node is not classified and traverse routine should recurse into node contents.
          */
         function tryClassifyNode(node: Node): boolean {
-            if (isJSDocTag(node)) {
+            if (isJSDocNode(node)) {
                 return true;
             }