### Description

`stats x = count`  throws error `unknown column [count]` which is confusing since stats does not allow aliasing for existing columns but only points to aggregate functions.
Hence why the message should be `incorrect function declaration count, you forgot to add the parantheisis`. 
Same approach when dealing with a typo: `stats x = cont(*)` - `Unkown aggregate function cont - did you mean count()?`

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/analysis/Verifier.java
if (failures.isEmpty()) {
            gatherMetrics(plan);
        }
        return failures;
    }
    private static void checkAggregate(LogicalPlan p, Set<Failure> failures) {
        if (p instanceof Aggregate agg) {
            agg.aggregates().forEach(e -> {
                var exp = e instanceof Alias ? ((Alias) e).child() : e;
                if (exp instanceof AggregateFunction aggFunc) {
                    Expression field = aggFunc.field();
                    
                    if ((field instanceof FieldAttribute
                        || field instanceof MetadataAttribute
                        || field instanceof ReferenceAttribute
                        || field instanceof Literal) == false) {
                        failures.add(
                            fail(
                                e,
                                "aggregate function's field must be an attribute or literal; found ["
                                    + field.sourceText()
                                    + "] of type ["
                                    + field.nodeName()
                                    + "]"
                            )
                        );
                    }
                } else if (agg.groupings().contains(exp) == false) { 
                    failures.add(
                        fail(