handle missing webview gracefully

[empratyush]

currently app crashes if there is no web view provider installed in device.

2022-05-12 15:13:26.594 1251-1670/? W/WebViewUpdater: creating relro file timed out 2022-05-12 15:13:26.733 3105-3105/? E/WebViewFactory: Chromium WebView package does not exist android.webkit.WebViewFactory$MissingWebViewPackageException: Failed to load WebView provider: No WebView installed at android.webkit.WebViewFactory.getWebViewContextAndSetProvider(WebViewFactory.java:334) at android.webkit.WebViewFactory.getProviderClass(WebViewFactory.java:398) at android.webkit.WebViewFactory.getProvider(WebViewFactory.java:211) at android.webkit.WebView.getFactory(WebView.java:2467) at android.webkit.WebView.ensureProviderCreated(WebView.java:2462) at android.webkit.WebView.setOverScrollMode(WebView.java:2527) at android.view.View.<init>(View.java:4536) at android.view.View.<init>(View.java:4668) at android.view.ViewGroup.<init>(ViewGroup.java:597) at android.widget.AbsoluteLayout.<init>(AbsoluteLayout.java:55) at android.webkit.WebView.<init>(WebView.java:636) at android.webkit.WebView.<init>(WebView.java:581) at android.webkit.WebView.<init>(WebView.java:564) at android.webkit.WebView.<init>(WebView.java:551) at java.lang.reflect.Constructor.newInstance0(Native Method) at java.lang.reflect.Constructor.newInstance(Constructor.java:334) at android.view.LayoutInflater.createView(LayoutInflater.java:647) at com.android.internal.policy.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:58) at android.view.LayoutInflater.onCreateView(LayoutInflater.java:720) at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:788) at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730) at android.view.LayoutInflater.rInflate(LayoutInflater.java:863) at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:824) at android.view.LayoutInflater.inflate(LayoutInflater.java:515) at android.view.LayoutInflater.inflate(LayoutInflater.java:423) at app.grapheneos.pdfviewer.databinding.PdfviewerBinding.inflate(PdfviewerBinding.java:71) at app.grapheneos.pdfviewer.databinding.PdfviewerBinding.inflate(PdfviewerBinding.java:65) at app.grapheneos.pdfviewer.PdfViewer.onCreate(PdfViewer.java:218) at android.app.Activity.performCreate(Activity.java:6975) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892) at android.app.ActivityThread.-wrap11(Unknown Source:0) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593) at android.os.Handler.dispatchMessage(Handler.java:105) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread.main(ActivityThread.java:6541) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)