Implement multimodal position encoder

...src/org/futo/inputmethod/latin/xlm/BatchInputConverter.kt

java/src/org/futo/inputmethod/latin/xlm/LanguageModel.java

native/jni/org_futo_inputmethod_latin_xlm_LanguageModel.cpp

native/jni/src/ggml/LanguageModel.cpp

native/jni/src/ggml/LanguageModel.h

native/jni/src/ggml/llama.cpp