Check for focused window before raising 'no focused window' ANR

Previously, we were relying on the dispatcher trying to send a focused
event prior to raising ANR due to no focused window.

So, the previous expected behavior was:
1. A key comes in, and there is no focused window
2. ANR timer starts
3. Focused window appears
4. We try to dispatch the key again, and realize there's a focused
window
5. We stop the ANR timer

However, there are cases when the pending key event gets dropped. For
example, this could happen if the user touches another application. That
would lead to the following sequence of events:
1. A key comes in, and there is no focused window
2. ANR timer starts
3. User touches another application, and the pending key gets dropped
4. Focused window appears
5. We don't try to dispatch the pending key anymore (since nothing is
pending)
6. We raise the "no focused window" ANR, even though we have a focused
window (and don't even have a focused event to dispatch anymore).

Solution: always check for focused window presence before raising the
"no focused window" ANR. This way, we will no longer rely on other events
happening for this ANR to be functioning correctly.

Bug: 164754075
Bug: 167780081
Test: atest inputflinger_tests
Change-Id: I70162d507fa7d65132c83fcba96ad9931e373647
Merged-In: I70162d507fa7d65132c83fcba96ad9931e373647
Signed-off-by: Akash Srivastava <akashniki@gmail.com>
Signed-off-by: DennySPb <dennyspb@gmail.com>
Signed-off-by: Anushek Prasal <anushekprasal@gmail.com>
Signed-off-by: Simão Gomes Viana <devel@superboring.dev>