### 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/src/test/java/org/elasticsearch/xpack/esql/optimizer/LogicalPlanOptimizerTests.java
import org.elasticsearch.xpack.esql.expression.predicate.operator.comparison.In;
import org.elasticsearch.xpack.esql.parser.EsqlParser;
import org.elasticsearch.xpack.esql.plan.logical.Dissect;
import org.elasticsearch.xpack.esql.plan.logical.Enrich;
import org.elasticsearch.xpack.esql.plan.logical.Eval;
import org.elasticsearch.xpack.esql.plan.logical.Grok;
import org.elasticsearch.xpack.esql.plan.logical.TopN;
import org.elasticsearch.xpack.esql.plan.logical.local.EsqlProject;
import org.elasticsearch.xpack.esql.plan.logical.local.LocalRelation;
import org.elasticsearch.xpack.esql.plan.logical.local.LocalSupplier;
import org.elasticsearch.xpack.ql.expression.Alias;
import org.elasticsearch.xpack.ql.expression.Attribute;
import org.elasticsearch.xpack.ql.expression.Expression;
import org.elasticsearch.xpack.ql.expression.Expressions;
import org.elasticsearch.xpack.ql.expression.FieldAttribute;
import org.elasticsearch.xpack.ql.expression.Literal;
import org.elasticsearch.xpack.ql.expression.NamedExpression;
import org.elasticsearch.xpack.ql.expression.Nullability;
import org.elasticsearch.xpack.ql.expression.ReferenceAttribute;
import org.elasticsearch.xpack.ql.expression.predicate.logical.And;
import org.elasticsearch.xpack.ql.expression.predicate.logical.Or;
import org.elasticsearch.xpack.ql.expression.predicate.nulls.IsNotNull;
import org.elasticsearch.xpack.ql.expression.predicate.regex.RLikePattern;
import org.elasticsearch.xpack.ql.expression.predicate.regex.WildcardPattern;
import org.elasticsearch.xpack.ql.index.EsIndex;
import org.elasticsearch.xpack.ql.index.IndexResolution;
import org.elasticsearch.xpack.ql.plan.logical.Aggregate;
import org.elasticsearch.xpack.ql.plan.logical.EsRelation;
import org.elasticsearch.xpack.ql.plan.logical.Filter;
import org.elasticsearch.xpack.ql.plan.logical.Limit;