Refactor JerkTracker and MotionPredictor for better testing.

Changes include renaming forgetFactor to alpha.

Test: atest libinput_tests
Bug: 266747654
Bug: 353161308
Flag: com.android.input.flags.enable_prediction_pruning_via_jerk_thresholding
Change-Id: Icd056d36a3d7894c6c9b4b957233002ad961a9a1
diff --git a/libs/input/TfLiteMotionPredictor.cpp b/libs/input/TfLiteMotionPredictor.cpp
index b401c98..5250a9d 100644
--- a/libs/input/TfLiteMotionPredictor.cpp
+++ b/libs/input/TfLiteMotionPredictor.cpp
@@ -283,7 +283,7 @@
             .distanceNoiseFloor = parseXMLFloat(*configRoot, "distance-noise-floor"),
             .lowJerk = parseXMLFloat(*configRoot, "low-jerk"),
             .highJerk = parseXMLFloat(*configRoot, "high-jerk"),
-            .jerkForgetFactor = parseXMLFloat(*configRoot, "jerk-forget-factor"),
+            .jerkAlpha = parseXMLFloat(*configRoot, "jerk-alpha"),
     };
 
     return std::unique_ptr<TfLiteMotionPredictorModel>(