TouchpadInputMapper: Add gesture property provider

Gesture properties are configurable parameters used by the gestures
library [0]. These will be used for per-device tuning and to implement
various touchpad settings. The property provider gives Android an
interface with which to get and set property values.

[0]: https://chromium.googlesource.com/chromiumos/platform/gestures/+/refs/heads/main/docs/gesture_properties.md

Bug: 251196347
Test: atest inputflinger_tests
Test: on device with some hacky test code
Change-Id: I7723dcbabf29e13c8ab0907c71e5dd1faa766b45
diff --git a/services/inputflinger/tests/Android.bp b/services/inputflinger/tests/Android.bp
index 58a5c31..af40fed 100644
--- a/services/inputflinger/tests/Android.bp
+++ b/services/inputflinger/tests/Android.bp
@@ -55,6 +55,7 @@
         "LatencyTracker_test.cpp",
         "NotifyArgs_test.cpp",
         "PreferStylusOverTouch_test.cpp",
+        "PropertyProvider_test.cpp",
         "TestInputListener.cpp",
         "UinputDevice.cpp",
         "UnwantedInteractionBlocker_test.cpp",