Added configuration for indexing of product information

Indexing of product information for the Product Projection Search and the Product Suggestions endpoints is now configurable via the Project endpoint. Using these endpoints is only possible if indexing has been activated for the Project and the search index has been built. Otherwise, the API replies with a 400 Bad Request error to requests on these endpoints.

• [API] Added searchIndexing field to Project.
• [API] Added Search Indexing Configuration for products to Project.
• [API] Added Search Indexing Configuration Values for status to Search Indexing Configuration.
• [API] Added Change Product Search Indexing Enabled update action to Project endpoint.
• [API] Added SearchDeactivated and SearchIndexingInProgress Errors.
• [GraphQL API] Added following types ChangeProjectSettingsProductSearchIndexingEnabled, SearchIndexingConfiguration, SearchIndexingConfigurationValues, SearchIndexingStatus.
• [GraphQL API] Added searchIndexing field to ProjectProjection type.
• [GraphQL API] Added input field changeProductSearchIndexingEnabled to ProjectSettingsUpdateAction type.

The following changes were introduced in terms of GraphQL SDL:

extend type ProjectProjection {
  searchIndexing: SearchIndexingConfiguration
}

extend input ProjectSettingsUpdateAction {
  changeProductSearchIndexingEnabled: ChangeProjectSettingsProductSearchIndexingEnabled
}

input ChangeProjectSettingsProductSearchIndexingEnabled {
  enabled: Boolean!
}

type SearchIndexingConfiguration {
  products: SearchIndexingConfigurationValues
}

type SearchIndexingConfigurationValues {
  status: SearchIndexingStatus
}

enum SearchIndexingStatus {
  Activated
  Indexing
  Deactivated
}