The nixpkgs-unstable channel's programs.sqlite was used to identify
packages producing exactly one binary, and these automatically added
to their package definitions wherever possible.
Bump scenebuilder to 19.0.0 as the latest release 20.0.0 depends on
jdk20, which is not packaged in nixpkgs yet.
Since version 15 the build system for scenebuilder was switched from
gradle to maven.
Additionally this commit switches to using a jre which bundles
openjfx. This used to be the default but was changed in ce6bc62,
which prevented scenebuilder from starting.
pkgs.writeTextFile doesn't like spaces in filenames.
This is fixed in #162246, but other tools will probably dislike
spaces in .desktop file names as well, and that PR will take forever,
so let's fix this anyway.
