dshowsrcwrapper: fix DirectShow caps negotiation and set capture pin caps

dshowsrcwrapper: fix DirectShow caps negotiation and set capture pin caps

Some cameras (IDS) have broken DirectShow drivers which incorrectly fill some
fields in the VIDEOINFOHEADER structure; comparison between suggested and
supported media types in CBaseRenderer should ignore deprecated and/or not
essential fields; additionaly explicitely setting the mediatype for the capture
pin before trying to connect it works around another IDS driver bug, and
should have been already done anyway.

https://bugzilla.gnome.org/show_bug.cgi?id=765428