Has this feature been discussed and generally agreed?

Initial discussion here: #2423 (comment)

Describe the solution you'd like

• Check that there is no technical reason to name the package like that
• Rename jamulus_3.8.2_ubuntu_amd64.deb to jamulus_3.8.2_amd64.deb
• Rename headless version accordingly
• Replace _ by - for headless to match the package name.
• grep the source for required updates (autobuild scripts use ubuntu)

Reasoning: We provide the .deb to support Debian and Ubuntu. .deb already hints that it targets these distributions. Adding ubuntu is confusing.

Describe alternatives that have been considered

Keep as-is