Idea: Search multiple pre-edits for Pinyin

Search multiple pre-edits at the same time, and arrange all candidate words in order of scoring.

![](https://user-images.githubusercontent.com/18661883/136894072-ecb3a6f0-6747-498c-b226-266644af7785.jpg)

![](https://user-images.githubusercontent.com/18661883/136898520-d41b2069-1819-4c45-9f19-603847b9f7ea.jpg)

https://github.com/fcitx/fcitx5/discussions/356