Move `java/preprocessor` to Gradle #105

Job	Run time
Test Processing	1m 30s
(linux/aarch64) Create Processing Build	7m 59s
(linux/x64) Create Processing Build	8m 47s
(windows/x64) Create Processing Build	11m 42s
(macos/x64) Create Processing Build	6m 46s
(macos/aarch64) Create Processing Build	3m 11s
	39m 55s

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