Add environment information to pov-project.json metadata

[wtwhite]

Some PoVs (at least CVE-2016-2510, CVE-2015-6420 and CVE-2015-7501) require particular environment variables to be set, especially the JDK to use in JAVA_HOME or they won't work (e.g., tests will be skipped). This information should be tracked in the pov-project.json metadata for each PoV, so that it can be automatically applied by shadedetector without having to remember the right -env command-line parameter.

• Add element to schema
• Add info to relevant CVEs' pov-project.json files

Some relevant info (commands with -env parameters) in https://github.com/jensdietrich/shadedetector/blob/main/scripts.zip.

This is an extension of #24.

[wtwhite]

Ideally we want to make some environment variables, like JAVA_HOME for setting the JDK to use, configurable at a higher level so that they work across different environments. E.g., to run on JDK 8, the run-on-java8.properties inside scripts.zip specifies

JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_311.jdk/Contents/Home

while I need

JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-amd64

on my Linux VM.

[wtwhite]

Resolved by adding jdkVersion to the Cue schema for pov-project.json, and by adding values for it, in #29 + #30 + #31.