feat: implement UI for logging out (#638)

* feat: implement UI for logging out

* feat: use old style dialogs for logout confirmation

* feat: implement manage sessions

* feat: implement session logout success dialog

* feat: use snjs alert for revoking sessions confirmation

* fix: make OtherSessionsLogout easier to read

app/assets/javascripts/preferences/components/PreferencesGroup.tsx

@@ -0,0 +1,24 @@
+import { FunctionComponent } from 'preact';
+import { HorizontalSeparator } from '@/components/shared/HorizontalSeparator';
+
+const HorizontalLine: FunctionComponent<{ index: number; length: number }> = ({
+  index,
+  length,
+}) => (index < length - 1 ? <HorizontalSeparator classes="my-4" /> : null);
+
+export const PreferencesGroup: FunctionComponent = ({ children }) => (
+  <div className="bg-default border-1 border-solid rounded border-gray-300 px-6 py-6 flex flex-col">
+    {Array.isArray(children)
+      ? children
+          .filter(
+            (child) => child != undefined && child !== '' && child !== false
+          )
+          .map((child, i, arr) => (
+            <>
+              {child}
+              <HorizontalLine index={i} length={arr.length} />
+            </>
+          ))
+      : children}
+  </div>
+);