[Feature] Add `--neovim-bin` to select `nvim` binary path

[pidgeon777]

As the title says, it would be nice to add an argument to the Nvy executable so that it is possible to specify the nvim binary path (as implemented for example in Neovide).

[underscoreHao]

I've raised a PR for this. Feel free to try it out :)

[pidgeon777]

@underscoreHao Great! Are the Windows binaries available somewhere?

[underscoreHao]

PR hasn't been reviewed yet, but you can build the project yourself from my PR. I've also changed the README with example use. If you don't want want to build the project yourself shoot me an e-mail and I'll send you a binary including the change so you can test it out.

[RMichelsen]

Closed via #117