XWIKI-22222: Add the concept of "request effective author"

...atform-oldcore/src/checkstyle/checkstyle-suppressions.xml

...xpn/xwiki/internal/web/EffectiveAuthorSetterListener.java

.../java/com/xpn/xwiki/render/ScriptXWikiServletRequest.java

...ldcore/src/main/java/com/xpn/xwiki/web/PreviewAction.java

...m-oldcore/src/main/java/com/xpn/xwiki/web/SaveAction.java

...src/main/java/com/xpn/xwiki/web/WrappingXWikiRequest.java

...oldcore/src/main/java/com/xpn/xwiki/web/XWikiRequest.java

.../src/main/java/com/xpn/xwiki/web/XWikiServletRequest.java

.../main/java/com/xpn/xwiki/web/XWikiServletRequestStub.java

...atform-oldcore/src/main/resources/META-INF/components.txt

...re/src/test/java/com/xpn/xwiki/doc/XWikiDocumentTest.java

...dcore/src/test/java/com/xpn/xwiki/web/SaveActionTest.java

.../org/xwiki/wysiwyg/script/WysiwygEditorScriptService.java