D3D_FEATURE_LEVEL_11_0 is not offically documented on MSDN to be a requirement
of DXGI duplicator APIs. So instead of using D3D_FEATURE_LEVEL_11_0 as a
requirement in D3dDevice::Initialize(), this change adds a
ScreenCapturerWinDirectx::SupportedFeatureLevel() function to retrieves minimum
and maximium for further reference (in HostTraits to control the experiment).
BUG=314516
Review-Url: https://codereview.webrtc.org/2468083002
Cr-Commit-Position: refs/heads/master@{#14962}