Fix libjack.so.0 detection for openSUSE

[tresf]

Fixes nightly installs so that they'll start on openSUSE

• Move libjack.so.0 from usr/lib/lmms/optional to usr/lib/jack (cosmetic decision)
• Switch app-hooks/jack-apphook.sh to prefer ldd instead
• Symlink libdb alongsize jack

Background:

The bug is caused by #7686 where we stopped looking in sbin for ldconfig however this PR changes the script to use ldd instead (a technique preferred after working on #7686 for reliability purposes).

The bug also exposed a new problem with our launcher; for systems that DO need our jack-apphook workaround, libdb-5.3.so is missing, which prevents LMMS from starting. This is solved by placing a symlink for libdb-5.3.so adjacent to libjack.so.0. We do this dynamically (preferring ldd again) for when this version inevitably changes.

Closes #7689

[tresf]

Testing:

Tests are a bit crude. I test WITH jack and WITHOUT jack. To simulate a system without jack, I simply move the binary, e.g:

1. Test with jack

   ~/lmms-1.3.0-alpha.1.765+pr7690.gee47f1942-linux-x86_64.AppImage

2. Test WITHOUT jack
   i. Move jack out of the way and start LMMS

   sudo mv /lib/x86_64-linux-gnu/libjack.so.0 /lib/x86_64-linux-gnu/libjack.so.0_bak && \
   ~/lmms-1.3.0-alpha.1.765+pr7690.gee47f1942-linux-x86_64.AppImage && \
   sudo mv /lib/x86_64-linux-gnu/libjack.so.0_bak /lib/x86_64-linux-gnu/libjack.so.0

   ii. Select "portaudio" from the audio devices, ensure no crash.

Status	OS	Arch
✅ PASS	Ubuntu 22.04	x86_64
✅ PASS	openSUSE TW	x86_64
✅ PASS	KDE Neon 2025	x86_64
✅ PASS	Manjaro Linux	x86_64
✅ PASS	Fedora 41	x86_64
✅ PASS	openSUSE TW	aarch64
✅ PASS	Ubuntu 24.04	aarch64