winaccessibility: replace CoCreateInstance with direct instantiation

This is an alternative (to 732ec36edfd09d2091d70c4d71b5f182fe279c45)
solution to the "CoCreateInstance does not work" problem:
replace all CoCreateInstance calls with equivalent calls to create
the components directly.

Since the only reason why this COM stuff needs to be registered
at all is that AccObject uses CoCreateInstance() to create its
COM objects, another possible solution appears to be to simply link
the libraries and instantiate the COM objects directly, without COM.

The only difference appears to be that CoCreateInstance would
automatically add proxy objects in case the COM objects reside in a
single-threaded appartment; not sure if that is relevant here.

Change-Id: I8ffb8af501f6084f3145fa4d4f53366a070e1691
Reviewed-on: https://gerrit.libreoffice.org/6792
Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>