Add Java 9 Stream APIs

[niloc132]

Partial #9547

[niloc132]

https://github.com/niloc132/gwt/actions/runs/5315644262/jobs/9624263435 shows successful build in all three tested Java runtime versions.

[niloc132]

@zbynek so it seems that Java8 has the same bug that GWT had here previously, so my new test above is failing in legacy dev mode.

import java.util.stream.DoubleStream;
import java.util.Arrays;

class Test {
        public static void main(String[] args) {
                int[] callCount = { 0 };
                double[] values = DoubleStream.iterate(0, val -> {
                        callCount[0]++;
                        return val + 1;
                }).limit(5).toArray();
                
                System.out.println(callCount[0]);
                System.out.println(Arrays.toString(values));
        }
}

In Java 11+, this results in

4
[0.0, 1.0, 2.0, 3.0, 4.0]

But in Java 8 (both my local copy and the build that the GHA runner is using), this yields:

5
[0.0, 1.0, 2.0, 3.0, 4.0]

Excitingly, Java 8 only has this bug for IntStream, DoubleStream, and LongStream, just plain Stream has the same behavior in 8 and 11/17:

import java.util.stream.Stream;
import java.util.Arrays;

class Test {
        public static void main(String[] args) {
                int[] callCount = { 0 };
                Integer[] values = Stream.iterate(0, val -> {
                        callCount[0]++;
                        return val + 1;
                }).limit(5).toArray(Integer[]::new);
                
                System.out.println(callCount[0]);
                System.out.println(Arrays.toString(values));
        }
}

4
[0, 1, 2, 3, 4]

[niloc132]

https://github.com/niloc132/gwt/actions/runs/6792333097 All current tests pass.