LocationBarController improvements

There are several scenarios where we should request that the browser doesn't hide its UI when in auto mode, including:

- SecurityStatus.securityLevel indicates a degraded status.
- The renderer is unresponsive.

We should also review some of the conditions in https://chromium.googlesource.com/chromium/src.git/+/master/chrome/android/java/src/org/chromium/chrome/browser/tab/TopControlsVisibilityDelegate.java#31. This logic should exist in Oxide so that we don't have to expose too many low-level internals (we don't want to expose things like isFocusedNodeEditable, for example).

The behaviour probably doesn't need to be configurable.

For the unresponsive renderer case we'll need some browser-side logic to override the headerbar position, as this is normally driven by the renderer compositor (which we can assume won't be producing any frames in this case).