Improving SimplifyExpr pass and dataflow pattern matcher for Relay

Development
#1

I plan to give a sequence of PRs to improve/simplify SimplifyExpr pass and dataflow pattern matcher for Relay. The goal of this post is to keep track of the progresses and to discuss with the community.

Checklist:

[] improve&simplify the optimization of clip. [#15068]

[] improve&simplify the optimization of transpose&reshape.

[] improve&simplify the optimization of cast.

[] improve&simplify the optimization of constant.

[] improve dataflow pattern.

#2

I would like to make general optimizations. I decide to improve dataflow pattern first. I file a pre-RFC in https://discuss.tvm.apache.org/t/on-the-applications-of-the-composition-of-dataflow-patterns/15344?u=kfeng123