Use comphelper::SequenceAsHashMap

Change-Id: I398881187001393a84e407157041d3a7d254b708
DOCX import: handle <w:alias> for the date SDT

Change-Id: I4a58fd9fc1db4e0fd3f9e2142fc208cec9f99f9d
DOCX export: handle <w:alias> for the date SDT

Change-Id: I97d4331a5e49815cc03e8579b50a076b37530f96