Make header (workbook) export and worksheet export clearer.

Change-Id: I9540fa32ca6a4ce041e15b272a049fcdf267fb0c
Split FillAsHeader into FillAsHeaderBinary and FillAsHeaderXml.

To reduce complexity in each method, and remove records that are
specific to binary export form the Xml variant.

Change-Id: I6c66054b99dd8cded5767610f2390952b59caf23
Split FillAsTable into Binary and Xml variants in the same manner.

And remove BIFF-only records from the Xml variant.

Change-Id: Ia18cc079d9a9249fbbe0c328b14b719fba8d6bbf