Update Autofill's usage of BrowserAccessibilityState on Android

This CL updates how the Autofill Assistant checks whether or not a
service has requested spoken feedback on Android.

With this CL we continue our efforts to centralize the functionality of
BrowserAccessibilityState and keep important business logic out of
client classes. Rather than allowing classes to fetch the entirety of
the AccessibilityServiceInfo and perform their own operations (which
is often nuanced and prone to errors), we are favoring the approach of
surfacing the requested information directly to the client. In this
case, the Autofill Assistant is interested in knowing if any running
apps have requested spoken feedback, which can be provided with a simple
boolean rather than passing an aggregated AccessibilityServiceInfo. We
add a method for Autofill Assistant to fetch this information directly.

AX-Relnotes: N/A
Bug: 1362100
Change-Id: I1a540720caa90c7e312fc41f25f65e1e2ad54e6d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3957855
Commit-Queue: Mark Schillaci <mschillaci@google.com>
Reviewed-by: Sergio Vila Prado <sergiovila@google.com>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1061795}