[FIX] Allow multiple namespaces if available
[FIX] Allow multiple namespaces if available

Some modules don't support multiple namespaces (for example
query+allpages) but it's possible that the generator factory sets it to
multiple namespaces. This also emits a warning if the namespace is
defined for a generator which does not support it.

Bug: T76794
Change-Id: I486d06fa6e03692f7c05725b22319e192b5d62c2

hasteur/g13bot_tools_new,npdoty/pywikibot,h4ck3rm1k3/pywikibot-core,smalyshev/pywikibot-core,hasteur/g13bot_tools_new,hasteur/g13bot_tools_new,npdoty/pywikibot,emijrp/pywikibot-core,trishnaguha/pywikibot-core,darthbhyrava/pywikibot-local,icyflame/batman,xZise/pywikibot-core,happy5214/pywikibot-core,jayvdb/pywikibot-core,TridevGuha/pywikibot-core,h4ck3rm1k3/pywikibot-core,jayvdb/pywikibot-core,wikimedia/pywikibot-core,valhallasw/pywikibot-core,wikimedia/pywikibot-core,magul/pywikibot-core,VcamX/pywikibot-core,happy5214/pywikibot-core,magul/pywikibot-core,PersianWikipedia/pywikibot-core,Darkdadaah/pywikibot-core,Darkdadaah/pywikibot-core