### Description

Evals that introduce aliased can be simplified by extracting them into a project (and thus signaling there's no underlying processing).

The following eval:
`eval x = a + 1, y = x, z = y + 1, y = z, w = y + 1`
can be converted into:
`eval x = a + 1, z = a + 1 + 1, w = a + 1 + 1 | project x, z, z as y, w`

This helps fuse the project with other projections/aggs downstream.
x-pack/plugin/esql/qa/testFixtures/src/main/java/org/elasticsearch/xpack/esql/CsvTestUtils.java
/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0; you may not use this file except in compliance with the Elastic License
 * 2.0.
 */
package org.elasticsearch.xpack.esql;
import org.apache.lucene.sandbox.document.HalfFloatPoint;
import org.apache.lucene.util.BytesRef;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.time.DateFormatters;
import org.elasticsearch.compute.data.Block;
import org.elasticsearch.compute.data.BlockFactory;
import org.elasticsearch.compute.data.BlockUtils;
import org.elasticsearch.compute.data.BlockUtils.BuilderWrapper;
import org.elasticsearch.compute.data.ElementType;
import org.elasticsearch.compute.data.Page;
import org.elasticsearch.core.Booleans;
import org.elasticsearch.core.Tuple;
import org.elasticsearch.logging.Logger;