UI: Add virtual camera to UI

Adds a virtual camera button to the main user interface.  If virtual
camera is not installed, it will not add the button.  On Windows, it
detects whether the virtual camera filters are properly registered, and
will only add the button if the virtual camera filter is confirmed
registered.

Also adds a virtual camera option to the auto-configuration wizard,
which will just simply set the user's resolution/scale to 1920x1080 at
30 FPS.

UI/window-basic-auto-config.cpp

@@ -69,6 +69,18 @@ AutoConfigStartPage::AutoConfigStartPage(QWidget *parent)
 	ui->setupUi(this);
 	setTitle(QTStr("Basic.AutoConfig.StartPage"));
 	setSubTitle(QTStr("Basic.AutoConfig.StartPage.SubTitle"));
+
+	OBSBasic *main = OBSBasic::Get();
+	if (main->VCamEnabled()) {
+		QRadioButton *prioritizeVCam = new QRadioButton(
+			QTStr("Basic.AutoConfig.StartPage.PrioritizeVirtualCam"),
+			this);
+		QBoxLayout *box = reinterpret_cast<QBoxLayout *>(layout());
+		box->insertWidget(2, prioritizeVCam);
+
+		connect(prioritizeVCam, &QPushButton::clicked, this,
+			&AutoConfigStartPage::PrioritizeVCam);
+	}
 }
 
 AutoConfigStartPage::~AutoConfigStartPage()
@@ -78,7 +90,9 @@ AutoConfigStartPage::~AutoConfigStartPage()
 
 int AutoConfigStartPage::nextId() const
 {
-	return AutoConfig::VideoPage;
+	return wiz->type == AutoConfig::Type::VirtualCam
+		       ? AutoConfig::TestPage
+		       : AutoConfig::VideoPage;
 }
 
 void AutoConfigStartPage::on_prioritizeStreaming_clicked()
@@ -91,6 +105,11 @@ void AutoConfigStartPage::on_prioritizeRecording_clicked()
 	wiz->type = AutoConfig::Type::Recording;
 }
 
+void AutoConfigStartPage::PrioritizeVCam()
+{
+	wiz->type = AutoConfig::Type::VirtualCam;
+}
+
 /* ------------------------------------------------------------------------- */
 
 #define RES_TEXT(x) "Basic.AutoConfig.VideoPage." x