public int getConsumedLength() {
		return (int) streamPos;
	}
ImageInputStream for reading images that wraps a MemBuffer to get the bytes.  Adds a method
to find out how many bytes were read by the imageReader to read the image.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/data/MemBufferImageInputStream.java