[Feature] Name the Rogue unlisted scratch buffers used by diagnostics, action selection etc.

[asmodeus812]

There are quite a few rogue singleton/cached scratch buffers created by coc.nvim for different purposes, diagnostics, action selection, etc, which could use a clear name instead of them being just the default [scratch] buffer, this is mostly used when we do ls! At the very least some coc related filetype name could also be set for those as well.