Extract Gesture handling code and test it

Similarly to the HardwareState logic, extracting this code makes things
a bit clearer and easier to test.

Bug: 251196347
Test: m inputflinger_tests && \
    $ANDROID_HOST_OUT/nativetest64/inputflinger_tests/inputflinger_tests \
    --gtest_filter='*HardwareStateConverterTest*'
Test: atest inputflinger_tests
Change-Id: I6902e052fc5e193228aca4378587413b22889b26
diff --git a/services/inputflinger/reader/Android.bp b/services/inputflinger/reader/Android.bp
index 1535df3..f3b680b 100644
--- a/services/inputflinger/reader/Android.bp
+++ b/services/inputflinger/reader/Android.bp
@@ -61,6 +61,7 @@
         "mapper/accumulator/MultiTouchMotionAccumulator.cpp",
         "mapper/accumulator/SingleTouchMotionAccumulator.cpp",
         "mapper/accumulator/TouchButtonAccumulator.cpp",
+        "mapper/gestures/GestureConverter.cpp",
         "mapper/gestures/GesturesLogging.cpp",
         "mapper/gestures/HardwareStateConverter.cpp",
     ],