Consider adding an executor for vimux

[sbosnick]

It may be useful to add a third executor for the RustRunnables support that makes use of the preservim/vimux plugin for vim/tmux integration.

I have a version of this working locally (which is reproduced below). If this is a good fit for rust-tools.nvim I would be happy to prepare a pull request. If not then feel free to close this issue.

function M.execute_command(command, args, cwd)
  local full_command = utils.chain_commands({
    utils.make_command_from_args("cd", { cwd }),
    utils.make_command_from_args(command, args),
  })

  vim.fn.VimuxRunCommand(full_command)
end

[simrat39]

Feel free to PR!