PRO-7846: Layout widget

[myovchev]

DO NOT MERGE UNTIL AFTER RELEASE

• Add Layout widget support
• Update styles
• Remove obsolete lib

[linear]

PRO-7846 Update all starter kits to use the layout widget.

[BoDonkey]

I don't quite get the second area on the default page. Why break video out to a standalone area?

[boutell]

I know this is only a draft and I am reviewing prematurely so this is a comment, not a blocker.

I think you should use 12 steps, and also explicitly configure the column widget's allowed contents even if it's the same as the default, so that it is easier for developers to understand how to add widgets to it. Otherwise layout feels like a black box and people reading Bob's documentation site won't really know what to do to add their very first custom widget.

[boutell]

Use 12

[myovchev]

Not appropriate here, it's tested and feels right in the context of the space it has.

[myovchev]

The Default page has 12. This also showcases the option override.

[myovchev]

@boutell Explicit define so that it's clear how to modify.

[myovchev]

I don't quite get the second area on the default page. Why break video out to a standalone area?

@BoDonkey It's a visual thing in the diff view. The widget list is

          widgets: {
            '@apostrophecms/rich-text': {},
            '@apostrophecms/image': {},
            '@apostrophecms/video': {}
          }

[boutell]

This allows only one level of layouts. Please demo nested layouts in a way that doesn't allow infinite nesting, and does restrict steps in a nested layout. (This means a subclass is needed.)

See the nested-layout branch for a working example although not in the lineage of this PR.