[JExtract/JNI] Add support for variables #706

Job	Run time
Test (Java) (macos swift:6.1.2 jdk:corretto)	2m 43s
Test (Java) (jammy swift:6.1.2 jdk:corretto)	2m 58s
Benchmark (JMH) (jammy swift:6.1.2 jdk:corretto)	7m 19s
Test (Swift) (jammy swift:6.1.2 jdk:corretto)	5m 46s
Test (Swift) (macos swift:6.1.2 jdk:corretto)	3m 30s
Sample JavaDependencySampleApp (jammy swift:6.1.2 jdk:corretto)	5m 23s
Sample JavaProbablyPrime (jammy swift:6.1.2 jdk:corretto)	4m 40s
Sample JavaKitSampleApp (jammy swift:6.1.2 jdk:corretto)	4m 40s
Sample SwiftAndJavaJarSampleLib (jammy swift:6.1.2 jdk:corretto)	4m 34s
Sample SwiftKitSampleApp (jammy swift:6.1.2 jdk:corretto)	5m 33s
Sample JavaSieve (jammy swift:6.1.2 jdk:corretto)	2m 1s
Sample JavaDependencySampleApp (macos swift:6.1.2 jdk:corretto)	5m 18s
Sample JExtractJNISampleApp (jammy swift:6.1.2 jdk:corretto)	5m 26s
Sample JavaKitSampleApp (macos swift:6.1.2 jdk:corretto)	4m 55s
Sample JavaSieve (macos swift:6.1.2 jdk:corretto)	3m 8s
Sample SwiftKitSampleApp (macos swift:6.1.2 jdk:corretto)	5m 17s
Sample JExtractJNISampleApp (macos swift:6.1.2 jdk:corretto)	5m 14s
Sample SwiftAndJavaJarSampleLib (macos swift:6.1.2 jdk:corretto)	4m 22s
soundness / Shell check	32s
Sample JavaProbablyPrime (macos swift:6.1.2 jdk:corretto)	4m 57s
soundness / Documentation check	33s
soundness / YAML lint check	4s
soundness / License headers check	7s
soundness / Unacceptable language check	6s
soundness / Broken symlinks check	3s
soundness / Format check	0s
soundness / Python lint check	7s
soundness / API breakage check	0s
	1h 29m 16s

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