MM-22845: Added support for permalink previews. (#17796)

* MM-22845: Added support for permalink previews.

* MM-22845: Adds license to new file.

* MM-22845: Adds endpoint to retrieve multiple posts by id.

* MM-22845: Fix for deleted post.

* MM-22845: Adds config setting for permalink previews.

* MM-22845: Adds API test for new endpoint.

* MM-22845: Fix typo.

* MM-22845: Tests that post create or updated via App get the previewed_post prop.

* MM-22845: Tests for matching permalinks.

* MM-22845: Adds PreparePostForClient test for permalink previews.

* MM-22845: Embeds entire post in permalink metadata.

* MM-22845: Filter WS message payload of created and edited post based on permissions.

* MM-22845: Runs app layer generator.

* MM-22845: Lint check fix.

* MM-22845: Adds feature flag.

* MM-22845: Clones WS message.

* MM-22845: Removes knowledge of permalink from LinkMetadata table. Removes knowledge of user id from post embedding methods in favour of a 'sanitize' method/step.

* MM-22845: Handle nil post metadata.

* MM-22845: Switch to cloning post.

* MM-22845: Removes unused code.

* MM-22845: Refactor.

* MM-22845: Reverts whitespace change.

* MM-22845: Removes unnecessary code.

* MM-22845: Removes unnecessary function.

* MM-22845: Warn but don't error if permalinked referenced post or channel is not found.

* MM-22845: Fix for clone method.

* MM-22845: Fix for clone method.

* MM-22845: Updates translations.

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/config.go

@@ -303,6 +303,7 @@ type ServiceSettings struct {
 	GoogleDeveloperKey                                *string  `access:"site_posts,write_restrictable,cloud_restrictable"`
 	DEPRECATED_DO_NOT_USE_EnableOnlyAdminIntegrations *bool    `json:"EnableOnlyAdminIntegrations" mapstructure:"EnableOnlyAdminIntegrations"` // Deprecated: do not use
 	EnableLinkPreviews                                *bool    `access:"site_posts"`
+	EnablePermalinkPreviews                           *bool    `access:"site_posts"`
 	RestrictLinkPreviews                              *string  `access:"site_posts"`
 	EnableTesting                                     *bool    `access:"environment_developer,write_restrictable,cloud_restrictable"`
 	EnableDeveloper                                   *bool    `access:"environment_developer,write_restrictable,cloud_restrictable"`
@@ -413,6 +414,10 @@ func (s *ServiceSettings) SetDefaults(isUpdate bool) {
 		s.EnableLinkPreviews = NewBool(true)
 	}
 
+	if s.EnablePermalinkPreviews == nil {
+		s.EnablePermalinkPreviews = NewBool(true)
+	}
+
 	if s.RestrictLinkPreviews == nil {
 		s.RestrictLinkPreviews = NewString("")
 	}