comphelper::SequenceAsHashMap: throw IllegalArgumentException

...instead of IllegalTypeException (where the latter is not a RuntimeException).
Fixes cid#707218, cid#1224993, etc., and reverts previous fix
358f5280e0f6afb968edc295d8f1dce55f05e18f "Fix coverity#1224993 w/o breaking
JunitTest_framework_unoapi."

Change-Id: I13ce153e1513749fb0be2ee8e560cec86a30c5ba