@ #484 | should make vagrant plugin can install by command

[hieptranquoc]

connect #484
Please review this PR, thx you!

[CLAassistant]

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[hieptranquoc]

example config in teracy-dev-essential

- _id: "essential-1"
      name: vagrant-libvirt
      # version: "" # empty means latest by default.
      state: "installed" # empty means do nothing.
      enabled: true

      # Add config args if you need to install by command
      plugin_vars:
        # example
        configure_args: with-libvirt-include=/usr/local/include/libvirt with-libvirt-lib=/usr/local/lib
        # If you have issues about gem, add gem config you need:
        # example
        # gem_home: "~/.vagrant.d/gems"
        # GEM_PATH:
        # PATH:
        # Some key: value

      # Add options to install command
      # see more at https://www.vagrantup.com/docs/cli/plugin.html#plugin-install
      # command_opts:
        # example
        # plugin-version: '< 0.0.43'
        # local:

[hieptranquoc]

Examples cases need to install by command:
https://github.com/vagrant-libvirt/vagrant-libvirt#possible-problems-with-plugin-installation-on-linux

CONFIGURE_ARGS='with-ldflags=-L/opt/vagrant/embedded/lib with-libvirt-include=/usr/local/include/libvirt with-libvirt-lib=/usr/local/lib' GEM_HOME=~/.vagrant.d/gems GEM_PATH=$GEM_HOME:/opt/vagrant/embedded/gems PATH=/opt/vagrant/embedded/bin:$PATH vagrant plugin install vagrant-libvirt

[hoatle]

This is still a little specific use case, we'll review and consider merging this when there are at least 2 use cases (2 plugins) that require the changes.

With the vagrant-libvirt plugin use case, let users manage to install it themselves for now.