Unable to rename sidebar-imported sample-track content

### Bug Summary
There is no method that can rename an imported sample in a sample-track. The sample gets the diskname, and that cant be changed. The actual sample-track-button is how ever named _Sample-track_, and not the disk-name.
The name on the button _can_ be changed

#### Steps to reproduce
Browse to a sample from sidebar, and choose _open-in-new-sample-track_
You get something like

#### Expected behavior
Right-clicking the sound-clip should offer the same naming-options as we have for right-clicking a midi-clip
Context of Sample-track:

Context of midi-track:

#### Actual behavior
No options

#### Affected LMMS versions
At least 1.3

Start with the sidebar's open-in-new-sample-track path and inspect how the sample-track button and sound-clip context menus are built. Compare those options with the midi-clip context menu shown in the issue. Done means a sidebar-imported sample offers the same naming options and its displayed sample name can be changed.

Written by the indexing model from the issue text.