Lazy-load tie-point data

When using the ProductIO API, tie-points and also other annotation datasets and metadata is read in entirely each time a product is opened. The opening of product files shall be as light-weight as possible thus loading of data shall be deferred to the point in time when it is actually needed (lazy-loading, see BEAM-679).This may drastically reduce runtime performance of the file-open process.

This improvement requires an extension of the ProductReader interface:

interface ProductReader {
     ...
    void readTiePointGridRasterData(TiePointGrid tpg,
                            int destOffsetX, int destOffsetY,
                            int destWidth, int destHeight,
                            ProductData destBuffer, ProgressMonitor pm) throws IOException;
     ...
}