Truncation fails if new size is larger than the current file size

[SailReal]

As FileChannel.html#truncate() of the Java NIO API doesn't follow the POSIX standard by not extending a file if it is shorter (by using zero bytes), we run into the following issue cryptomator/cryptomator#2218

From the doc:

If the given size is less than the file's current size then the file is truncated, discarding any bytes beyond the new end of the file. If the given size is greater than or equal to the file's current size then the file is not modified. In either case, if this channel's file position is greater than the given size then it is set to that size.

of https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/nio/channels/FileChannel.html#truncate(long)