Volume control issues with Pipewire

[Sunspark-007]

Describe the bug
The volume control doesn't display correctly and doesn't adjust correctly compared to pulseaudio.

Two observations are made for this issue:

1. On a fresh install which defaults to Pipewire, clicking play on a flac stream the volume icon in audacious the slider is displaying 50% but you can hear that it's actually playing at 100% and the KDE system settings audio panels shows that the volume coming from Audacious is actually 100% and not 50%.
2. Moving the mouse wheel, doesn't move the volume in even increments like 5%. It moves oddly and you end up with numbers like 63% in the kde audio panel instead of 65%, etc.

Steps to reproduce
Clean flatpak user data, try pipewire volume adjustments while looking at kde audio panel. Then repeat process with pulseaudio.

Expected behavior
Pipewire volume handling should operate like pulseaudio. Pulseaudio for example starts playback displaying 100% not 50% and mouse wheel moves the volume in 5% increments.

Additional information

• Audacious version and interface (Qt / GTK / Winamp): Audacious 4.4 flatpak, looks like QT
  Operating System: SteamOS 3.6.20 Build: 20241030.1
  KDE Plasma Version: 5.27.10
  KDE Frameworks Version: 5.115.0
  Qt Version: 5.15.12
  Kernel Version: 6.5.0-valve22-1-neptune-65-g9a338ed8a75e (64-bit)
  Graphics Platform: X11