Dependency updates iteration 1

[jackofdiamond5]

Related to #1294

This PR updates packages of the root CLI project, as well as the CLI package sub-project.

Updating yargs required some changes in all of the CLI's commands, as the newest version of the package is used and the API is quite different to what we've been using so far. Additionally, strict types have been introduced everywhere possible for each individual command. Also, some new tests have been introduced for the help command since we did not have full coverage for all available commands. Finally, the fs-extra package has been removed and the code has been updated to use fs instead,

Currently there is a problem with the CLI where running a command with aliased options fails - #1312

Notes for testing:

• All commands should be tested one at a time to ensure that they work as expected.

  • Checklist:
    • add command
    • build command
    • config command
    • doc command
    • generate command
    • list command
    • help command
      • global (e.g. ig --help)
      • for individual commands (e.g. ig add --help)
    • new command
    • quickstart command
    • start command
    • test command
    • upgrade command

• A project should be generated with sass/less styles and it should work just fine (all styles files should be copied properly) - this is due to the removal of fs-extra where it was used to copy the styles to the generated project's directory. Now custom logic handles this and it should be tested.

[coveralls]

coverage: 71.361% (+0.5%) from 70.833%
when pulling 7b7fd67 on bpenkov/dep-updates-iter1
into 53ffeec on master.