Revisit post index mapping data types

[oscarssanchez]

Is your enhancement related to a problem? Please describe.

We could improve some of the data types in mappings.

Describe the solution you'd like

• Thumbnail src from text to keyword : https://github.com/10up/ElasticPress/blob/develop/includes/mappings/post/7-0.php#L445 (this is similar to other URL data like https://github.com/10up/ElasticPress/blob/develop/includes/mappings/post/7-0.php#L386)
• Facet field is always sent in the post mapping, it probably shouldn't if the facet feature is deactivated, as there would be no practical purpose having it: https://github.com/10up/ElasticPress/blob/develop/includes/mappings/post/7-0.php#L245
• ep_custom_result taxonomy should not have a facet field.
• Post type. Should it have text fields instead of just a keyword ? https://github.com/10up/ElasticPress/blob/develop/includes/mappings/post/7-0.php#L371
• ID, menu_order and other numeric data to keyword https://github.com/10up/ElasticPress/blob/develop/includes/mappings/post/7-0.php#L266: Elastic recommends using keyword instead of integer or long if we are not expecting to perform range queries https://www.elastic.co/guide/en/elasticsearch/reference/current/keyword.html

Designs

Describe alternatives you've considered

Additional context

• We need to make sure to update all mapping files
• A reindex will be needed