Added a CSP headers filter to RESTBase config.
Added a CSP headers filter to RESTBase config.

Bug: T158822
Change-Id: I95612651b4a2101677171ac2f511e27ecf11ad3b

wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant