Gets keyboard layout info from user space when available.

The layout info consists of a BCP 47 conformant language tag and a
layout type such as "qwerty" or "azerty". They will be used to
initialize the input device.

This is currently used by uinput virtual keyboard to pass in layout
information.

Bug: 237537306
Test: atest inputflinger_tests
Change-Id: Icfc30f1afb0f88dd704d1d598d62a300a032b0f5
diff --git a/services/inputflinger/tests/FakeInputReaderPolicy.h b/services/inputflinger/tests/FakeInputReaderPolicy.h
index faa9c01..862ff0b 100644
--- a/services/inputflinger/tests/FakeInputReaderPolicy.h
+++ b/services/inputflinger/tests/FakeInputReaderPolicy.h
@@ -58,6 +58,8 @@
     void addDeviceTypeAssociation(const std::string& inputPort, const std::string& type);
     void addInputUniqueIdAssociation(const std::string& inputUniqueId,
                                      const std::string& displayUniqueId);
+    void addKeyboardLayoutAssociation(const std::string& inputUniqueId,
+                                      const KeyboardLayoutInfo& layoutInfo);
     void addDisabledDevice(int32_t deviceId);
     void removeDisabledDevice(int32_t deviceId);
     void setPointerController(std::shared_ptr<FakePointerController> controller);