[ESQL] Migrate PropagateEquals optimization (elastic#106627)

Relates to elastic#105217

This copies the PropagateEquals logical optimization into ESQL, following the pattern established in elastic#106499. I've copied the optimization rule into the ESQL version of OptimizerRules, and the tests into OpitmizerRulesTests, and changed the imports &c to point to the appropriate ESQL classes instead of their QL counterparts.

I expect to have several more PRs following this pattern, for the remaining logical optimizations that touch the binary comparison logic. I'm intending to make separate PRs for each, in the interest of making them easier to review.

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/optimizer/LogicalPlanOptimizer.java

@@ -82,7 +82,6 @@
 import static java.util.Collections.singleton;
 import static org.elasticsearch.xpack.esql.expression.NamedExpressions.mergeOutputExpressions;
 import static org.elasticsearch.xpack.ql.expression.Expressions.asAttributes;
-import static org.elasticsearch.xpack.ql.optimizer.OptimizerRules.PropagateEquals;
 import static org.elasticsearch.xpack.ql.optimizer.OptimizerRules.TransformDirection;
 import static org.elasticsearch.xpack.ql.optimizer.OptimizerRules.TransformDirection.DOWN;
 
@@ -126,7 +125,7 @@ protected static Batch<LogicalPlan> operators() {
             new BooleanSimplification(),
             new LiteralsOnTheRight(),
             // needs to occur before BinaryComparison combinations (see class)
-            new PropagateEquals(),
+            new org.elasticsearch.xpack.esql.optimizer.OptimizerRules.PropagateEquals(),
             new PropagateNullable(),
             new BooleanFunctionEqualsElimination(),
             new org.elasticsearch.xpack.esql.optimizer.OptimizerRules.CombineDisjunctionsToIn(),