ibus-bamboo: add at 0.8.4

[minhhut]

Summary

• add ibus-bamboo at v0.8.4 (https://github.com/BambooEngine/ibus-bamboo/releases/tag/v0.8.4-RC1)
• known issue with Wayland native (see BambooEngine/ibus-bamboo#44)

Test Plan

• Install ibus and run "IBus Preferences"
• Add Vietnamese - Bamboo from Input Method tab
• Add "Keyboard Layouts" plugin/widge to see the input switch icon
• Play around with language switch and many options from IBus Bamboo popup menu
• Focus on text input from browser, terminal or other app
• Type "xin chào các bạn"

Checklist

• [x] Package was built and tested against unstable