Add support for the new QUERY verb in HTTP

[bkoelman]

The idea is to add action methods to the JsonApiDotNetCore base controllers to support the new HTTP QUERY verb, which is an HTTP-safe method (cachable) that takes the query string in the request body to overcome size limits. The HTTP spec is currently in draft.

At this time, ASP.NET only added the enum member and there's no mention in the JSON:API spec. While this could already be implemented today, we should probably wait until ASP.NET fully supports it, such as by parsing the request body into HttpContext.Request.QueryString and HttpContext.Request.Query.

Please upvote if you care about this.