Implement EZP-23396: Elasticsearch: Implement Fulltext criterion for Content search

This PR resolves https://jira.ez.no/browse/EZP-23396

This implements FullText criterion visitor for Content Search.
`meta_all` is added to the nested fields document as a custom `_all` field for each translation. Root document `_all` field is disabled and will not be used.

Reasoning: Since we need to index Content in multiple languages, aggregating all full text data in a root `_all` would pollute full text search when multiple languages are involved, producing matches on languages that are not available for display. `meta_all` will be further employed in language filtering implementation to limit matching to a single language or specific set of languages (coming up next).

Modification to the database fixture was needed because Elasticsearch SE does not index Content names per translation. Followup: https://jira.ez.no/browse/EZP-23508