Refactored the impersonation dialog (#994)

Moved the impersonation dialog from a new tab into a popup window. The instance page is refreshed with the new user's context, but the location remains the same.

Author: johndahl-now

Browser Bookmarklets/Impersonation/impersonation.js

@@ -0,0 +1,8 @@
+# User Impersonation
+When a user impersonates another user, the page is redirected to the home page for the new user. This bookmarklet will open the impersonation page in a popup window so the user impersonation can be completed without redirecting the paging being viewed. After selecting the new user, the popup will close and the instance page will refresh with the new user context.
+
+This was updated from a new tab to the popup based on the "Quick Login to current instance" bookmarklet by OrgovanGeza.
+
+```js
+javascript:let impWin=window.open("/impersonate_dialog.do", "Impersonation", "scrollbars=no,resizable=no,status=no,location=no,toolbar=no,menubar=no,width=300,height=300,left=100,top=100");setInterval(()=>{if(!impWin.location.pathname.includes("impersonate")){impWin.close();window.location.reload();};},500);
+```