Fix for deeplink crash when preparing webview preview (#2116)

Task/Issue URL: https://app.asana.com/0/414709148257752/1205793869765618/f
Tech Design URL:
CC:

Description:
When launching the app from deeplink the webView size can be 0,0 causing UIGraphicsBeginImageContextWithOptions to crash

DuckDuckGo/TabViewController.swift

@@ -1094,7 +1094,8 @@ extension TabViewController: WKNavigationDelegate {
 
     func preparePreview(completion: @escaping (UIImage?) -> Void) {
         DispatchQueue.main.async { [weak self] in
-            guard let webView = self?.webView else { completion(nil); return }
+            guard let webView = self?.webView,
+                  webView.bounds.height > 0 && webView.bounds.width > 0 else { completion(nil); return }
             UIGraphicsBeginImageContextWithOptions(webView.bounds.size, false, UIScreen.main.scale)
             webView.drawHierarchy(in: webView.bounds, afterScreenUpdates: true)
             if let jsAlertController = self?.jsAlertController {