JSON schema examples property

Let's override the componentpluginmanager again in ui_patterns_library, and make it extends ui_patterns one

DONE:

• componentpluginmanager added with first draft of JSON schema examples property and otehr stuff
• split of templates (not in the scope of this issue, but let's do it anyway)

What do we do if there a not the same number of examples in props?

• We ignore missing examples? (current situation)
• We repeat the last example?
• We do a matrix? For example, 2 props, one with 2 examples, one with 3 examples: 3 stories.?

This branch also have commits about splitting library templates !

Splitting library templates task is moved to #3438387: [2.0.0-alpha3] Split Library templates into smaller ones

Moved to beta1

See also #3455354: [2.0.0-beta4] Add a stories specific discovery

Still working on it.

Testing with https://www.drupal.org/project/prototype and not convinced because the results are not visually great.

Moved to beta2, with the related Library issues. However, we may cancel this change if the results don't match the added complexity.

Because we plan to extends the plugin manager, let's wait to see what will happen with the service decorator in #3469808: [2.0.0-beta5] Use decorator instead overwriting the component plugin service

Let's start again, with a service decorator instead of the first proposal, following #3469808: [2.0.0-beta5] Use decorator instead overwriting the component plugin service

let's do it ASAP because display builder needs it for early beta phase

This may be related to #3551586: ComponentPluginManager decorator incorrectly calls parent instead of decorated service because we need a decorator in ui_patterns_library

Testing with SDC themes found in the wild. Some crazy stuff over there. So, let's try to extends the logic.