XWIKI-9620: WikiStream script service allow anyone to export/import anything

(cherry picked from commit ffdb6264c3d32b1fe1d712dafe679f581e43aac9)

Conflicts:
	xwiki-platform-core/xwiki-platform-wikistream/xwiki-platform-wikistream-instance/xwiki-platform-wikistream-instance-script/src/main/java/org/xwiki/wikistream/instance/script/InstanceWikiStreamScriptService.java