Add better validation of fieldset and disallow tensors

[jobergum]

We should add validation of the fields referenced in fieldset(s), currently we allow mixing tensor and regular fields which will generate a runtime exception (UnsupportedOperationException) when attempting to search the fieldset because tensors only accepts nearestNeighbor operator.

schema msmarco {
    document msmarco {
        
        field title type string {
            indexing: index | summary
            match: text
            index: enable-bm25
        }
        field body type string {
            indexing: index
            match: text
            index: enable-bm25
        }
        field vector type tensor<float>(x[512]) {
          indexing:summary|attribute
        }
    }
    fieldset default {
        fields: title, body, url, vector
    }
}

The above generates a unrelated deploy time warning which seem to be focused on attribute versus index match defaults (not sure why the message is printed twice).

vespa deploy .       
Uploading application package... done

Success: Deployed '.' with session ID 15
WARNING For schema 'msmarco', field 'vector': The matching settings for the fields in fieldset 'default' are inconsistent (explicitly or because of field type). This may lead to recall and ranking issues.
WARNING For schema 'msmarco', field 'vector': The normalization settings for the fields in fieldset 'default' are inconsistent (explicitly or because of field type). This may lead to recall and ranking issues.

But fails obviously at runtime with UnsupportedOperationException, secondary observation is that the error is buried in the payload of a 200 OK.

curl -v "http://127.0.0.1:8080/search/?language=en&timeout=10s&user-query=what+is+dad+bod&yql=select+%2A+from+msmarco+where+userInput%28%40user-query%29+and+url+contains+%28%7Bfilter%3Atrue%2Cranked%3Afalse%7D%22huffingtonpost.co.uk%22%29"
*   Trying 127.0.0.1:8080...
* Connected to 127.0.0.1 (127.0.0.1) port 8080 (#0)
> GET /search/?language=en&timeout=10s&user-query=what+is+dad+bod&yql=select+%2A+from+msmarco+where+userInput%28%40user-query%29+and+url+contains+%28%7Bfilter%3Atrue%2Cranked%3Afalse%7D%22huffingtonpost.co.uk%22%29 HTTP/1.1
> Host: 127.0.0.1:8080
> User-Agent: curl/7.84.0
> Accept: */*
> 
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Date: Sat, 11 May 2024 06:44:44 GMT
< Content-Type: application/json;charset=utf-8
< Vary: Accept-Encoding
< Content-Length: 4991
< 
{"root":{"id":"toplevel","relevance":1.0,"fields":{"totalCount":1},"coverage":{"coverage":100,"documents":996,"full":true,"nodes":1,"results":1,"resultsFull":1},"errors":[{"code":8,"summary":"Error in search reply.","source":"msmarco","message":"UnsupportedOperationException: