Substitution#getRexShuttle does not consider RexLiteral

Current Substitution#getRexShuttle does not take RexLiteral into consideration.
Thus below query & mv fails matching:

MV:
select deptno, sum(salary), sum(commission), sum(k)
from
  (select deptno, salary, commission, 100 as k
  from emps)
group by deptno

Query:
select deptno, sum(salary), sum(k)
from
  (select deptno, salary, 100 as k
  from emps)
group by deptno

The root cause is that ProjectToProjectUnifyRule compensates a Project which contains RexLiteral, but AggregateOnProjectToAggregateUnifyRule works only when the Project in query is a mapping
https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/plan/SubstitutionVisitor.java#L1357