UI: Add advanced scene collection importer

This replaces the previous Open File dialog for importing collections
with a window for importing many collections at once, based on the remux
window, along with support for importing from OBS Classic, XSplit
Broadcaster and from Streamlabs' fork. This also translates sources
between OSes that Studio supports.

UI/CMakeLists.txt

@@ -57,6 +57,7 @@ set(CMAKE_INCLUDE_CURRENT_DIR TRUE)
 set(CMAKE_AUTOMOC TRUE)
 
 find_package(Qt5Svg ${FIND_MODE})
+find_package(Qt5Xml ${FIND_MODE})
 
 find_package(FFmpeg REQUIRED COMPONENTS avcodec avutil avformat)
 
@@ -230,6 +231,7 @@ set(obs_SOURCES
 	window-basic-transform.cpp
 	window-basic-preview.cpp
 	window-basic-about.cpp
+	window-importer.cpp
 	window-namedialog.cpp
 	window-log-reply.cpp
 	window-projector.cpp
@@ -284,6 +286,7 @@ set(obs_HEADERS
 	window-basic-adv-audio.hpp
 	window-basic-transform.hpp
 	window-basic-preview.hpp
+	window-importer.hpp
 	window-namedialog.hpp
 	window-log-reply.hpp
 	window-projector.hpp
@@ -324,6 +327,19 @@ set(obs_HEADERS
 	qt-wrappers.hpp
 	clickable-label.hpp)
 
+set(obs_importers_HEADERS
+	importers/importers.hpp)
+
+set(obs_importers_SOURCES
+	importers/importers.cpp
+	importers/classic.cpp
+	importers/sl.cpp
+	importers/studio.cpp
+	importers/xsplit.cpp)
+
+source_group("importers\\Source Files" FILES ${obs_importers_SOURCES})
+source_group("importers\\Header Files" FILES ${obs_importers_HEADERS})
+
 set(obs_UI
 	forms/NameDialog.ui
 	forms/AutoConfigStartPage.ui
@@ -341,6 +357,7 @@ set(obs_UI
 	forms/OBSExtraBrowsers.ui
 	forms/OBSUpdate.ui
 	forms/OBSRemux.ui
+	forms/OBSImporter.ui
 	forms/OBSAbout.ui)
 
 set(obs_QRC
@@ -353,6 +370,8 @@ add_executable(obs WIN32
 	obs.manifest
 	${obs_SOURCES}
 	${obs_HEADERS}
+	${obs_importers_SOURCES}
+	${obs_importers_HEADERS}
 	${obs_UI_HEADERS}
 	${obs_QRC_SOURCES})
 
@@ -372,6 +391,7 @@ target_link_libraries(obs
 	libobs
 	Qt5::Widgets
 	Qt5::Svg
+	Qt5::Xml
 	obs-frontend-api
 	${FFMPEG_LIBRARIES}
 	${LIBCURL_LIBRARIES}