[2.0.7] Add third_party_settings to ui_patterns_slot_source schema

@grimreaper: Let's talk about that because you are the config schema fan.

Fixed.

What about this question: Is it OK this proposal is different from other definitions in Core?

layout_builder.section:
  type: mapping
  label: 'Layout section'
  mapping:
    ...
    third_party_settings:
      type: sequence
      label: 'Third party settings'
      sequence:
        type: '[%parent.%parent.%type].third_party.[%key]'

config_entity:
  type: mapping
  mapping:
    ...
    third_party_settings:
      requiredKey: false
      type: sequence
      label: 'Third party settings'
      sequence:
        type: '[%parent.%parent.%type].third_party.[%key]'

theme_settings:
  type: config_object
  mapping:
...
    third_party_settings:
      # Third party settings are always optional: they're an optional extension
      # point.
      requiredKey: false
      type: sequence
      label: 'Third party settings'
      sequence:
        type: theme_settings.third_party.[%key]

I was not aware theme settings also got third_party_settings, thinking about ui_styles_entity_status, ui_skins....

field_formatter:
  type: mapping
  label: 'Field formatter'
  mapping:
...
    third_party_settings:
      # Third party settings are always optional: they're an optional extension
      # point.
      requiredKey: false
      type: sequence
      label: 'Third party settings'
      sequence:
        type: field.formatter.third_party.[%key]

core.entity_form_display.*.*.*:
  type: config_entity
  label: 'Entity form display'
  mapping:
...
    content:
      type: sequence
      label: 'Field widgets'
      sequence:
        type: mapping
        label: 'Field widget'
        mapping:
 ...
          third_party_settings:
            # Third party settings are always optional: they're an optional extension
            # point.
            requiredKey: false
            type: sequence
            label: 'Third party settings'
            sequence:
              type: field.widget.third_party.[%key]

I think it is ok to not have automatically type: '[%parent.%parent.%type].third_party.[%key]', but in the current state, the sequence type needs to be specified.

We can do this:

--- a/config/schema/ui_patterns.schema.yml
+++ b/config/schema/ui_patterns.schema.yml
@@ -67,6 +67,12 @@ ui_patterns_slot_source:
     third_party_settings:
       type: sequence
       label: 'Third party settings'
+      sequence:
+        type: ui_patterns_slot_source.third_party_setting.[%key]
     _weight:
       type: weight
       label: 'Slot source weight'

And then do this in UI Patterns:

ui_patterns_slot_source.third_party_setting.ui_styles:
  label: 'UI Styles settings'
  type: ui_styles.selected_mapping

But this new policy make this kind of synchronous changes to cumbersome:

As discussed with @just_like_good_vibes seems working with ui_patterns 2.x-dev and 2.0.8 release, so need to come back and finish here when 2.0.8 is out.

https://www.drupal.org/project/display_builder/issues/3529260#comment-16... 📌 [1.0.0-alpha2] Flatten the Fields list Active

So, postponed.