No APPEND mode for opening file on Android

I have this code in Kotlin Multiplatform Mobile project:
```kotlin
dstFile.vfs.open(dstFile.path, VfsOpenMode.APPEND).use {
setPosition(rangeData?.startIndex ?: 0)
writeBytes(bytes)
}
```
and I get this error on Android:
```
java.lang.UnsupportedOperationException: APPEND not allowed
at sun.nio.fs.UnixChannelFactory.newAsynchronousFileChannel(UnixChannelFactory.java:172)
at sun.nio.fs.UnixFileSystemProvider.newAsynchronousFileChannel(UnixFileSystemProvider.java:200)
at java.nio.channels.AsynchronousFileChannel.open(AsynchronousFileChannel.java:253)
at java.nio.channels.AsynchronousFileChannel.open(AsynchronousFileChannel.java:311)
at korlibs.io.file.std.AsynchronousFileChannelVfs$openAsynchronousFileChannel$2.invokeSuspend(AsynchronousFileChannelVfs.kt:60)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:100)
at kotlinx.coroutines.internal.LimitedDispatcher$Worker.run(LimitedDispatcher.kt:124)
at kotlinx.coroutines.scheduling.TaskImpl.run(Tasks.kt:89)
at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:586)
at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:820)
at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:717)
at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:704)
```

Start in AsynchronousFileChannelVfs.kt at the openAsynchronousFileChannel call shown in the stack trace, and inspect how VfsOpenMode.APPEND is passed to Android's file channel. Reproduce the failure with the Kotlin Multiplatform Mobile example, then verify that APPEND opens successfully and preserves the requested write behavior without the UnsupportedOperationException.

Written by the indexing model from the issue text.