Add java.io.RandomAccessFile::getFD() #627

Job	Run time
rust_ci (ubuntu-latest, beta)	1m 20s
rust_ci (ubuntu-latest, stable)	1m 10s
rust_ci (macos-latest, beta)	1m 45s
rust_ci (macos-latest, stable)	1m 10s
rust_ci (windows-latest, stable)	3m 45s
rust_ci (windows-latest, beta)	3m 1s
	12m 11s

Provide feedback