Creating Express mode for generating applications(must have) and other artifacts(optional) through CLI

[shimks]

Description / Steps to reproduce / Feature proposal

There should be a mode for creating apps through CLI where users can expect everything to be done for them without having to configure anything through the prompts.

Acceptance Criteria

• Add an Automatic / Custom mode for selecting the project settings.
  • Appropriate Tests / Blog posts / etc.
• Figure out the optional prompts
  • how to pass answers to them.
• Maybe introduce a flag to specify the express mode
• App cli is a must have goal
  • other clis are stretch goals
• A blog post

Related PR

#1384

Discussion points

• How are we going to present this option to the users?
  • Through prompts?
  • Through flags/options?

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[dhmlau]

Getting the feedback from #1309 and team discussion, I think the general idea of each CLI command is to have express and custom mode, such that:

$ lb4 <<artifact>>
> express (<<prompt for minimal items>> )
   custom (<<customize everything>>)

Proposal for lb4 app command

• custom path would show what we're showing currently, asking:
  • project name
  • project description
  • project root directory
  • application class name
  • project build settings
• express path asks only project name, and keeping defaults for the rest, such that:
  • project name: (user defined)
  • project description: loopback4 example
  • project root directory: (same as project name)
  • application class name: (project_name+Application)
  • project build settings: enable tslint, prettier, mocha, loopbackBuild

[bajtos]

I think the proposed express mode is too express. For example, I don't think there is any good default value for a project description to use in the express mode.

The whole discussion (see #1309) was started because build settings are difficult to understand for new users. I think that's all we should hide behind express/custom mode.

I think the following prompts should remain unchanged:

$ lb4 app
? Project name: todo-app
? Project description: A simple todo app
? Project root directory: todo-app
? Application class name: TodoAppApplication

The custom/express prompt should be displayed after those initial questions were cleared and we are going to decide how to configure the build:

Currently:

? Select project build settings:  (Press <space> to select, <a> to toggle all, <i> to invert selection)
❯◉ Enable tslint
 ◉ Enable prettier
 ◉ Enable mocha
 ◉ Enable loopbackBuild

My proposal:

? What build steps would you like to enable: (Use arrow keys)
❯ All recommended (loopbackBuild, mocha, tslint, prettier) 
  Manually select features