All the 136 emoji dict files takes ~5.5MB, and it's already zlib compressed so it would increase the apk size by almost 5.5MB if we include them all. But Android only supports a handful of languages currently, and only English keyboard could use this emoji data.

This PR introduces a CMake variable FCITX5_MODULE_EMOJI_DICT_FILES, when set, would override emoji dict files to be installed.

Could be used like this:

set(FCITX5_MODULE_EMOJI_DICT_FILES
        en.dict
        zh.dict
        zh_Hant.dict
        zh_Hant_HK.dict
        ja.dict
        vi.dict
        )
# other options ...
add_subdirectory(fcitx5)