Implement KeyboardClassifier interface in rust

DD: go/project-imposter-android
This CL includes:
- Rust interface setup

Next CL to include:
- Basic categorization into alphabetic and non-alphabetic
- Updating categorization based on key presses

Test: atest --host libinput_rust_test
Test: atest inputflinger_tests
Bug: 263559234
Flag: com.android.input.flags.enable_keyboard_classifier_rust_impl
Change-Id: I52773be992ddd8efaa9546e0af8b0a78515d931c
diff --git a/services/inputflinger/reader/mapper/KeyboardInputMapper.h b/services/inputflinger/reader/mapper/KeyboardInputMapper.h
index f2d3f4d..bee2a99 100644
--- a/services/inputflinger/reader/mapper/KeyboardInputMapper.h
+++ b/services/inputflinger/reader/mapper/KeyboardInputMapper.h
@@ -61,7 +61,6 @@
     };
 
     uint32_t mSource{};
-    int32_t mKeyboardType{};
     std::optional<KeyboardLayoutInfo> mKeyboardLayoutInfo;
 
     std::vector<KeyDown> mKeyDowns{}; // keys that are down
@@ -85,8 +84,7 @@
     } mParameters{};
 
     KeyboardInputMapper(InputDeviceContext& deviceContext,
-                        const InputReaderConfiguration& readerConfig, uint32_t source,
-                        int32_t keyboardType);
+                        const InputReaderConfiguration& readerConfig, uint32_t source);
     void configureParameters();
     void dumpParameters(std::string& dump) const;