Update macOS setup script to use the tiff image in the installer bundle, as this is the type of background image expected and included by jpackage.
Convert Bisq-background.png to Bisq-background.tiff using imagemagick.
Fixed typo affecting jpackage option concatenation, where a missing "+" caused subsequent options to not be considered. Surround concatenated options with parentheses, to ensure such a typo in the future is marked as a syntax error, and therefore avoided.
Fix the logic used to determine the JDK 15 assets and download links. Pre-releases are now excluded, as well as openj9 binaries. The resulting assets are final releases of hotspot builds.
Extend the gradle script with tasks that use jpackage to generate Bisq binaries. The kind of binaries generated depend on the OS where this is executed.
The packaging of binaries can be started by calling:
./gradlew --console=plain packageInstallers
from the root project folder.
