### 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/PhysicalPlanOptimizerTests.java
assertEquals("first_name", wildcard.fieldName());
        assertEquals("*foo*", wildcard.value());
    }
    public void testPushDownNotLike() {
        var plan = physicalPlan("""
            from test
            | where not first_name like "%foo%"
            """);
        var optimized = optimizedPlan(plan);
        var topLimit = as(optimized, LimitExec.class);
        var exchange = asRemoteExchange(topLimit.child());
        var project = as(exchange.child(), ProjectExec.class);
        var extractRest = as(project.child(), FieldExtractExec.class);
        var source = source(extractRest.child());
        assertThat(source.estimatedRowSize(), equalTo(allFieldRowSize + Integer.BYTES));
        var boolQuery = as(sv(source.query(), "first_name"), BoolQueryBuilder.class);
        assertThat(boolQuery.mustNot(), hasSize(1));
        var tq = as(boolQuery.mustNot().get(0), TermQueryBuilder.class);
        assertThat(tq.fieldName(), is("first_name"));
        assertThat(tq.value(), is("%foo%"));
    }
    public void testEvalRLike() {
        var plan = physicalPlan("""
            from test
            | eval x = concat(first_name, "--")
            | where x rlike ".*foo.*"
            """);
        var optimized = optimizedPlan(plan);
        var topLimit = as(optimized, LimitExec.class);
        var exchange = asRemoteExchange(topLimit.child());