Turn selected pods into a scope

[lihebi]

This feature helps organize the canvas hierarchy. Specifically, it consists of two features:

1. a button to turn selected pods into a scope
2. a button to select all pods on the ROOT canvas

[senwang86]

1. a button to turn selected pods into a scope

Did PR #419 fully address this feature?

2. a button to select all pods on the ROOT canvas

Is PR #454 good enough for now?

[lihebi]

Both PRs addressed partially. I’d still like a direct way to do these operations.

In addition, we need one more feature alone this line: splice a scope into its parent scope.

[lihebi]

This is known as the splicing and raising in structural editing