Move DisplayBuildableInterface to a Provider plugin type

Problem/Motivation

Step by step, DisplayBuildableInterface is becoming big and messy:

  public static function getPrefix(): string;
  public static function getContextRequirement(): string;
  public static function checkInstanceId(string $instance_id): ?array;
  public function getBuilderUrl(): Url;
  public static function getUrlFromInstanceId(string $instance_id): Url;
  public static function getDisplayUrlFromInstanceId(string $instance_id): Url;
  public function getProfile(): ?ProfileInterface;
  public function getInstanceId(): ?string;
  public function initInstanceIfMissing(): void;
  public function getInitialSources(): array;
  public function getInitialContext(): array;
  public function getSources(): array;
  public function saveSources(): void;

And not discoverable, so we have added display_builder_provider_info hook.

Proposed resolution

Create a display_builder/Provider plugin type

With attribute discovery. Not configurable.

ProviderInterface:

• getProfile(): ProfileInterface (the one saved in config/content, not the one from Instance)
• getInstance(): InstanceInterface
• getInitialSources(): array;
• getContextRequirement(): string;
• getContext(): array; (renamed from getInitialContext())
• getSources(): array;
• saveSources(): void;
• getUrl(): Url (as a replacement of both getBuilderUrl() and getDisplayUrlFromInstanceId)
• getDisplayUrl(): Url (as a replacement of getDisplayUrlFromInstanceId)

We may not need this anymore:

• all static functions taking instance_id as parameter: checkInstanceId, getUrlFromInstanceId, getDisplayUrlFromInstanceId because we now work on instanciated plugins
• getPrefix(): not currently used outside the classes. Can be replaced by a plugin attribute.
• getInstanceId(): replaced by getInstance()->id() or something like that
• getInitialSources() : only used in InstanceStorage::createFromImplementation()
• initInstanceIfMissing(): because implementation always the same, can be moved to a base class

Move DisplayBuildableInterface implementation logic to 4 plugins

• modules/display_builder_entity_view/src/Plugin/display_builder/Provider/EntityView.php
• modules/display_builder_entity_view/src/Plugin/display_builder/Provider/ContentOverride.php
• modules/display_builder_page_layout/src/Plugin/display_builder/Provider/PageLayout.php
• modules/display_builder_views/src/Plugin/display_builder/Provider/ViewDisplay.php

Replace display_builder_provider_info by the plugin type manager

that's it