Bamboo (Vietnamese Input Method) engine support for Fcitx

Based on https://github.com/BambooEngine/bamboo-core

Released under LGPLv2.1+

Requires:
Fcitx 5, go.

Install:
$ mkdir build && cd build
$ cmake -DCMAKE_INSTALL_PREFIX=[prefix to fcitx5] ..
$ make
# make install
