### Description

Before ES 7.x it was possible to provide a list of fields by URL or BODY request for field_caps API.
https://www.elastic.co/guide/en/elasticsearch/reference/6.8/search-field-caps.html
`POST _field_caps
{
   "fields" : ["rating"]
}`

Starting from 7.x this feature was removed, and only one possible way it uses URI but in this case, it is possible to have an error 414 (Request-URI Too Long).

I would like to return this feature back.
server/src/main/java/org/elasticsearch/rest/action/RestFieldCapabilitiesAction.java
@Override
    public List<Route> routes() {
        return List.of(
            new Route(GET, "/_field_caps"),
            new Route(POST, "/_field_caps"),
            new Route(GET, "/{index}/_field_caps"),
            new Route(POST, "/{index}/_field_caps")
        );
    }