Make assertPosition a method of FakePointerController

This way it can be used in tests that aren't based on InputMapperTest.

Bug: 251196347
Test: m inputflinger_tests && \
    $ANDROID_HOST_OUT/nativetest64/inputflinger_tests/inputflinger_tests \
    --gtest_filter='*HardwareStateConverterTest*'
Test: atest inputflinger_tests
Change-Id: I39a7f08ac9b705d12e45acc3e3773b0046e80e5c
diff --git a/services/inputflinger/tests/FakePointerController.h b/services/inputflinger/tests/FakePointerController.h
index f00870f..d10cbcd 100644
--- a/services/inputflinger/tests/FakePointerController.h
+++ b/services/inputflinger/tests/FakePointerController.h
@@ -38,6 +38,8 @@
     int32_t getDisplayId() const override;
     void setDisplayViewport(const DisplayViewport& viewport) override;
 
+    void assertPosition(float x, float y);
+
 private:
     bool getBounds(float* outMinX, float* outMinY, float* outMaxX, float* outMaxY) const override;
     void move(float deltaX, float deltaY) override;