Ignoring `$NVIM_APPNAME` to generate files and directories

[uga-rosa]

Result from CocInfo

Describe the bug

In Neovim, $NVIM_APPNAME affects rtp, so the results of stdpath('config'), etc. also change. The configuration file ~/.config/${NVIM_APPNAME}/init.lua will be used, and so on. However, coc.nvim does not seem to take this into account, and :CocConfig opens ~/.config/nvim/coc-settings.json. Probably all the files and directories that coc.nvim automatically creates, besides :CocConfig, do not take $NVIM_APPNAME into account as well.

Reproduce the bug

We will close your issue when you don't provide minimal vimrc and we can't reproduce it

• Create file mini.vim with：

  set nocompatible
  set runtimepath^=/path/to/coc.nvim
  filetype plugin indent on
  syntax on
  set hidden

• Place mini.vim into ~/.config/test/init.vim

• Start (neo)vim with command: NVIM_APPNAME=test nvim

• :CocConfig

• :echo expand('%') shows the path of the configration file.

Screenshots (optional)

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[fannheyward]

coc-settings.json is located in stdpath('config'), other files created by coc.nvim are located in ~/.config/coc.