Add "orderby" to config schema definitions

Adding the orderby key will order sequences alphabetically in config exports for better readability and less confusing diffs.

See the change record: New orderby key added to configuration schema for sequences.

in entity_usage.settings.yml

entity_usage.settings:
  type: config_object
  mapping:
    // ... other config schema key definitions
    track_enabled_plugins:
      label: Enabled tracking plugins
      type: sequence
      orderby: value
      sequence:
        type: string

before adding the orderby:

track_enabled_plugins:
  - dynamic_entity_reference
  - link
  - linkit
  - layout_builder
  - entity_reference
  - entity_embed
  - html_link
  - block_field

after adding the orderby:

track_enabled_plugins:
  - block_field
  - dynamic_entity_reference
  - entity_embed
  - entity_reference
  - html_link
  - layout_builder
  - link
  - linkit