Import data tables from xlsx via ScDocumentImport.

Change-Id: Id3d526720f99b7557476915beab35b429ec97c1d
Create data-table directory and move the test file into it.

Change-Id: I1007525a7d2e1135f0388975f9cb7b0cef9b3142
Two new test cases for importing data tables from XLSX.

Change-Id: I87da806612ae50fe1d64b851c5180ff1792752cb