Add back a "restore last p5.sound version" toggle once 2.0 becomes default

[davepagurek]

Increasing Access

In #3513 (comment), we changed the behaviour of the p5.sound toggle because switching from 1.x to 2.x prevented you from using the new p5.sound.

Once 2.x is default and people are likely switching major versions less often, we discussed in the previous issue how this behaviour might again be desirable so that it's easier for users to try out different versions while being able to quickly go back to what they started with.

Feature enhancement details

We can undo some of the changes in this if need be: #3522