Explain verbose should include optimized physical plan

[NGA-TRAN]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
The Explain Verbose currently shows physical plan before its final optimized step that includes CoalesceBatches, RepartitionExec, and MergeExec operators. This is a request to show the plan that includes all physical operators that will be executed.

Describe the solution you'd like
If you look at this create_physical_plan, the explain is created in the create_initial_plan which happens before the optimize_plan is invoked. The explain should be created after the optimize_plan

[alamb]

Possibly related to #497

[Dandandan]

Also related: #221

[alamb]

Closed in #499