Ability to define custom ex commands

Is your feature request related to a problem? Please describe.
I use neovim integration, but I am unable to define the custom ex commands I use in neovim, and the commands defined in my ~/.config/nvim/init.vim are not respected. To give you a flavour, these are the ones I currently have defined for neovim:

command! W   :w
command! Wa  :wa
command! Wq  :wq
command! Wqa :wqa
command! E   :e

Describe the solution you'd like
I am able to define custom ex commands either in VSCode settings.json or have the ones in my neovim config respected.

Describe alternatives you've considered

Additional context
I'd be happy to have a go at implemeting this myself if this is something you'd accept a PR on and someone could point me in the right direction.

Start by reviewing how the extension reads VS Code settings.json and how it handles the user's ~/.config/nvim/init.vim. Compare those paths with the existing custom ex-command integration points, if any. Done means users can define custom ex commands in settings.json or have the listed Neovim commands respected.