Add __dir__ to DynamicAccessProxy

This restores tab-completion to objects proxied through
DynamicAccessProxy

news/fix_DAP_completion.rst

@@ -0,0 +1,24 @@
+**Added:**
+
+* <news item>
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* Added proxied ``__dir__`` method to ``DynamicAccessProxy`` to restore
+  tab-completion for objects that use the proxy (especially ``events``) 
+
+**Security:**
+
+* <news item>

xonsh/built_ins.py

@@ -1489,6 +1489,9 @@ class DynamicAccessProxy:
     def __call__(self, *args, **kwargs):
         return self.obj.__call__(*args, **kwargs)
 
+    def __dir__(self):
+        return self.obj.__dir__()
+
 
 class DeprecationWarningProxy:
     """Proxies access, but warns in the process."""