Create buffer in blocks mode

[martinwork]

Is your feature request related to a problem? Please describe.

Would it be possible to create a buffer without switching to Javascript?

Describe the solution you'd like

A block for control.createBuffer()

Additional context

Example https://makecode.microbit.org/_Rd8U542yEctE

[abchatra]

This is a good candidate for extension

[microbit-carlos]

Do blocks need to be in the toolbox to be able to exist? We could have an extension to have the blocks in the toolbox, but being able to write the code in the TypeScript view and be able to go back and forth would be useful as well.