Allow QZ Tray to work alongside older JREs

[tresf]

Some clients require a legacy JRE for other 3rd party products, but they often conflict with the requirements of QZ Tray.

Quoting @klabarge from a support request:

I've tested AdoptOpenJDK 11.0.3 (64-bit) + Oracle Java 6u18 (64-bit) installed on a Windows 10 PC. The installation was successful, however I was unable to launch the software. Assuming this is a requirement, we will look at our launcher logic to see if we can make any improvements.

I believe if we swap the JDK/JRE search order it would allow these to coexist. Since AdoptOpenJDK11 is the preferred runtime, this should be a sane change. The disadvantage will be developer machines that historically ran one version of the JDK and then a separate version of the JRE may be impacted. I consider this minor.

[tresf]

Closed via #504