Extract FakeInputDispatcherPolicy into a separate cpp file

It will be used by other tests that will be added in the future.

Bug: 210460522
Test: build
Change-Id: I36d6b5aef98e621d8193d72063e8c7ecddd567a3
diff --git a/services/inputflinger/benchmarks/Android.bp b/services/inputflinger/benchmarks/Android.bp
index 2d12574..4385072 100644
--- a/services/inputflinger/benchmarks/Android.bp
+++ b/services/inputflinger/benchmarks/Android.bp
@@ -11,6 +11,7 @@
 cc_benchmark {
     name: "inputflinger_benchmarks",
     srcs: [
+        ":inputdispatcher_common_test_sources",
         "InputDispatcher_benchmarks.cpp",
     ],
     defaults: [
@@ -31,6 +32,8 @@
     ],
     static_libs: [
         "libattestation",
+        "libgmock",
+        "libgtest",
         "libinputdispatcher",
     ],
 }