Create plugin bootstrapping generator

[nazarhussain]

Description

This generator will bootstrap a plugin and all its dependencies. The interface of the generator should be:

lisk generate:plugin <alias>

Motivation

User should be able to generate a skeleton of the plugin quickly. So he can explore the features which are provided with off-chain architecture. This one generator could be used to generate the plugin within application bootstrapped earlier.

Acceptance Criteria

• The generated plugin should be under plugins directory.
• The generated plugin should also be registered to the application
  -The plugin directory skeleton should be following:

  src/
    commands/
    app/
      plugins.ts  <-- require plugins and register 
      plugins/
        /plugin_name/      
          pluign_name.ts  <-- Plugin class default export 
          index.ts        <-- Export Plugin class and other functions if needed

• It should also generate the relevant test skeleton.

Additional Information

• The plugin source code should include load and unload methods
• The rest of plugin require data should be populated from package.json file.
• It should have a sample array of events but commented
• It should have a sample actions object but commented