[Intelephense] Support mounting in $HOME/intelephense/license.txt

[hbjydev]

I don't want to pass through my Intelephense license key through the Neovim config (it's public in my dotfiles repo), so could you expose a way to mount in a license key to $HOME/intelephense/license.txt in the LSP container?

Thanks! :D

[erikreinert]

We have an open PR already for this: #69