Cannot use WP-CLI inside the project

**Is your feature request related to a problem? Please describe.**
Cannot use WP-CLI inside the project built using this boilerplate.

**Describe the solution you'd like**
WP-CLI should be accessible from any directory inside the boilerplate.

**Describe alternatives you've considered**
Since with this boilerplate, the Wordpress core files are installed inside `public/wp/` directory, that needs to be specified with `--path` option in the all the `wp` commands.

It would be better if we can have a repository-wide configuration. That will save the user to specify it every time.

**Additional context**
Add any other context or screenshots about the feature request here.