Refactor use of services in InputMappers.

Create InputDeviceContext class to hide direct EventHub and
InputDevice accesses from InputMappers.

Test: atest inputflinger_tests libinput_tests
Change-Id: I05f9c808fc1a6f4c9207bd29fde50b76ec5655bb
diff --git a/services/inputflinger/reader/mapper/ExternalStylusInputMapper.h b/services/inputflinger/reader/mapper/ExternalStylusInputMapper.h
index 34f339a..1d42b30 100644
--- a/services/inputflinger/reader/mapper/ExternalStylusInputMapper.h
+++ b/services/inputflinger/reader/mapper/ExternalStylusInputMapper.h
@@ -27,7 +27,7 @@
 
 class ExternalStylusInputMapper : public InputMapper {
 public:
-    explicit ExternalStylusInputMapper(InputDevice* device);
+    explicit ExternalStylusInputMapper(InputDeviceContext& deviceContext);
     virtual ~ExternalStylusInputMapper() = default;
 
     virtual uint32_t getSources() override;