Crash can occur with SDRPlay API in place, but service stopped

[alphafox02]

sdrtrunk Version
Version 0.6.0 Alpha 4

Describe the bug
Crash in program without SDRPlay service running

To Reproduce
Steps to reproduce the behavior:

1. On linux, 22.04 aarch64 (most likely AMD64 too) have the SDRPlay 3.x API installed, but have the service stopped with sudo systemctl stop sdrplay.service
2. Start SDRTrunk from terminal and observe SDRtrunk finding the sdrplay.so file, but crashing due to service not running.

Expected behavior
SDRTrunk should continue to start and run even without sdrplay started, maybe just warn the user instead of crashing.

[DSheirer]

Resolved in PR #1514