[v4.x] Support for Copy & Paste of Custom Blocks in Rich Editor

[fukuhara-trust]

Currently, when I focus on a custom block in the v4 rich editor and copy it (e.g., using Ctrl + C), then try to paste it into the editor while the input area is focused (e.g., using Ctrl + V), nothing seems to be pasted.

Are there any plans to add support for copying and pasting custom blocks?

Thank you!