Support for InputDevice ViewBehavior

This change creates a struct within InputDeviceInfo to hold View related
behaviors of an input device. Currently, a single behavior is supported:
device.viewBehavior_smoothScroll. This can be specified in an IDC file
to hint clients of the InputDevice that they should animate scrolls for
motion events generated by the InputDevice.

Bug: 246946631
Test: add property in IDC, check API returns expected value
Test: atest frameworks/native/services/inputflinger/tests/InputReader_test.cpp
Change-Id: Ibe373cadc40d2a08116e787b744dd30812638edb
diff --git a/libs/input/input_flags.aconfig b/libs/input/input_flags.aconfig
index 174464d..ec7a284 100644
--- a/libs/input/input_flags.aconfig
+++ b/libs/input/input_flags.aconfig
@@ -111,3 +111,10 @@
   description: "Move user-activity poke rate-limiting from PowerManagerService to InputDispatcher."
   bug: "320499729"
 }
+
+flag {
+  name: "input_device_view_behavior_api"
+  namespace: "input"
+  description: "Controls the API to provide InputDevice view behavior."
+  bug: "246946631"
+}