[BE] remove cut-n-paste support

[senwang86]

Summary

The cut-n-paste was introduced in PR #165 , as the moveIntoScope #280 function was implemented, cut-n-paste seems unnecessary, this is a Better Engineering effort to reduce the tech debt.

• The cut button is removed from the toolbar in Code/Scope pod.

[lihebi]

We were talking about that cutting isn't necessary anymore. But after a second thought, I feel that cutting may still be useful in a few cases:

1. Cut once and paste many times
2. The cutting behavior is also slightly different from moving.
   • Cutting-n-pasting doesn't alter anything until clicked
   • Moving constantly changes the position of the pod being moved. Thus, DB and other peers see the changes in real-time.

[senwang86]

We were talking about that cutting isn't necessary anymore. But after a second thought, I feel that cutting may still be useful in a few cases:

1. Cut once and paste many times

2. The cutting behavior is also slightly different from moving.

   • Cutting-n-pasting doesn't alter anything until clicked
   • Moving constantly changes the position of the pod being moved. Thus, DB and other peers see the changes in real-time.

The moving effect of the cutting pod is very fancy and I like it, as it shows that "cutting" is taking place; I think copy-n-paste should apply the same effect to indicate that "copy" is happening.

I am OK with either choice, while I don't think cutting has a strong use case; If cutting isn't regularly used, we might think about moving the button from the toolbar to another location.

[senwang86]

PR #452 address the topic.