incremental highlighting support

[clangd]

incremental highlighting support

[sam-mccall]

A couple of related issues here:

• the old notification-based protocol ("theia protocol"). The protocal was always defined as incremental. Clangd 9 sent all tokens every time. Clangd 10 sends only the changed ones. 008da37 fixes coc-clangd to apply the diffs.
• the new request-based protocol (will be in LSP 3.16). Clangd will support both absolute and incremental requests. We should add support for this (probably to coc.nvim itself rather than coc-clangd).

[sam-mccall]

@fannheyward could you push a new release here so we can pick up this fix? (or grant https://www.npmjs.com/~sam-mccall rights to do that) Thanks!

(After that I'm not sure if you want to close this issue, or if you want to use it for work on supporting the new protocol)

[fannheyward]

New version has released, also invite you to npmjs as a maintainer.

[sam-mccall]

@fannheyward thanks a lot!