FileNotFoundException might be caused by race condition reading UFDR evidence

[lfcnassif]

While working on #1224, I noticed the return statement below might cause FNFE because the File got in the block right before can be deleted from disk when adding a new File to the cache since it has a max size:

IPED/iped-engine/src/main/java/iped/engine/io/ZIPInputStreamFactory.java

Lines 159 to 164 in ad61a6f

	synchronized (filesCache) {
	tmp = filesCache.get(path);
	}
	if (tmp != null) {
	return new SeekableFileInputStream(tmp.toFile());
	}

I have never seen this happen in practice, but it is possible. The fix is simply moving the return statement into the synchronized block.