Have an option of truncating invisible parts of clips

**Is your feature request related to a problem? Please describe.**
The size of the files is large for edited projects, as they contain unused data. The detach at silences menu item is not working as expected and was reported as a bug earlier #2051, #2312.
In a two-person interview, this can save as much as half of the space, for more people, even more! Using 3.0.5 I had around 700MB/s an hour after 3.3 the same project takes over 2GBs!

**Describe the solution you'd like**
I would like to have a new menu option that **truncates** the clips to the visible range. This can remove duplicate data from the project and free up lots of space and reduce processing times drastically.

**Describe alternatives you've considered**
Create a compressed backup format that is compressed and does not store excessive data, or support the creation of old-style backups.