Extend Silences

Split from https://forum.audacityteam.org/t/easy-way-to-add-silence/35483/1

Well, it does work but not perfectly.
I was able to extend the silences in the program to meet the minimum.
But what I noted there was a “thump” that hit about -30db when the additional time was added.
You couldn’t hear it but it bumped the VU meters. The timer and time remaining don’t work.
When the timer ran out it just sat for a couple minutes before it completed.

So overall, it works but needs some fine tuning.

Thanks guys.