Coc.nvim: Allow to config multiple workspace folders rootPattern lookup ordering

[jackysee]

Is your feature request related to a problem? Please describe.
Having a subfolder of client side code inside project, plugin like coc-prettier would need to resolve a correct workspace.

├── .git
├── server
│   ├── ...
├── client
│   ├── .pretteric.js
│   ├── package.json
│   ├── node_modules
│   │   ├── prettier

We can adopt the multiple workspace setting like,

    "coc.preferences.rootPatterns": ["package.json", ".vim", ".git", ".hg"]

But it seems that current lookup method would fail on nesting folder, i.e.
open vim at project (cwd), and then open file client/src/someFile.js, it will try:

• project/package.json --> not found
• project/.vim --> not found
• project/.git --> found! set as workspace folder

So plugin like coc-prettier won't get the correct config.

Describe the solution you'd like
A setting like coc.preferences.rootPatternLookupFolderFirst: true so that the look up order is

• project/package.json --> not found
• project/client/package.json --> found! set as workspace folder

[chemzqm]

No, you can start vim in client folder.