Currently the document themes are hardcoded and the new ones will
be only used in the current document. This is the first of the
series to make document theme user defined and stored in the user
and shared folders (just like other resources). This change adds
the configuration of the folder which will be used to search for
the document themes. By default the folders are located in the user
and shared profile folders.
Change-Id: I1388983804d012cd7f8575dfc96830451821f56e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/180379
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>