mobile-html: CSP: allow data: URIs
mobile-html: CSP: allow data: URIs

So the edit pencils and other images (icons) from the page library
are displayed.

Bug: T200464
Change-Id: Icf445fe0f1318e546a64e9c75543eafa2b944aa2

wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps