[WIP][GeneratorBundle] Commands to generate new website skeleton and default pageparts

[acrobat]

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Fixed tickets

This PR introduces 2 new maker commands to generate a new (improved for symfony 4) website skeleton and a new set of default pageparts. There is also a spacer pp added to allow setting custom spacings between pageparts. The functionality, to add this pagepart automatically after a pagepart is added, is disabled by default. Some work is needed to make this fully configurable.

TODO:

• [x] Make a region config option to enable the auto add of a spacer pp after a regular pp

kunstmaan_page_part:
    pagetemplates:
        homepage:
            name: "Home page"
            rows:
                - regions:
                    - { name: "main", span: 12, auto_spacer: true }
            template: "pages\\home_page\\pagetemplate.html.twig"

• [ ] Config value to specify the spacer pp FQCN
• [ ] Deprecate the old generator commands (default site + default pp's)
• [ ] Mark these commands as @experimental. To allow fast changes (that possibly break BC) in case of big issues
• [ ] Cleanup command output, better feedback to the user
• [ ] Check javascript to auto add the spacer (should append the spacer to the last added pp)
• [ ] Remove old cookie consent twig file (and includes)
• [ ] Default styling of quote pp
• [ ] Use the asset() twig function where we include images instead of hardcoded paths