Win Video Capture: add support for enumerating DirectShow WDM devices

Win Video Capture: add support for enumerating DirectShow WDM devices

DirectShow supports a certain type of Video Capture Cards, in general
video digitizers (a.k.a. Analog video capture cards). These cards need
extra configuration of the "remote" ports in and out. For this purpose,
the Windows Driver Model is used [1], where special DS Filters are
added upstream of the capture source.

This CL adds support for enumerating these devices, which will show up
as another camera in the system list.

Other posterior CLs will figure out other parts needed, namely:

- which "normal" Filter is associated to the WDM Filter, for the
purpose of capabilities enumeration.

- if the VideoCaptureDevice::Name passed to VideoCaptureDeviceWin
is labelled as being WDM, a slightly different capture graph is
needed.

For the Hauppage USB-Live 2, this means another camera called
"Hauppauge Cx23100 Crossbar", in addition to the normal "Hauppauge
USB-Live2"

[1] http://msdn.microsoft.com/en-us/library/windows/desktop/dd373405(v=vs.85).aspx

BUG=402684

Review URL: https://codereview.chromium.org/510723003

Cr-Commit-Position: refs/heads/master@{#292627}