Java: Add `GET`, `SET`, `INFO` and `PING` commands #510

Job	Run time
lint-rust	3m 52s
build-amazonlinux-latest (11)	4m 12s
build-amazonlinux-latest (17)	4m 27s
build-and-test-java-client (11, 6.2.14, ubuntu-latest)	3m 47s
build-and-test-java-client (11, 6.2.14, macos-latest)	7m 52s
build-and-test-java-client (11, 7.2.3, ubuntu-latest)	4m 20s
build-and-test-java-client (11, 7.2.3, macos-latest)	7m 41s
build-and-test-java-client (17, 6.2.14, ubuntu-latest)	3m 56s
build-and-test-java-client (17, 6.2.14, macos-latest)	11m 8s
build-and-test-java-client (17, 7.2.3, ubuntu-latest)	4m 16s
build-and-test-java-client (17, 7.2.3, macos-latest)	5m 43s
	1h 1m 14s

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