UI: Add the ability to create custom browser docks

Allows the ability for users to add custom browser widget docks that
they can use for their third party services if they feel the need,
mostly as a convenience tool so they don't have to open extra browsers
alongside the program.

UI/CMakeLists.txt

@@ -146,10 +146,12 @@ if(BROWSER_AVAILABLE_INTERNAL)
 	list(APPEND obs_PLATFORM_SOURCES
 		obf.c
 		auth-oauth.cpp
+		window-extra-browsers.cpp
 		)
 	list(APPEND obs_PLATFORM_HEADERS
 		obf.h
 		auth-oauth.hpp
+		window-extra-browsers.hpp
 		)
 
 	if(TWITCH_ENABLED)
@@ -324,6 +326,7 @@ set(obs_UI
 	forms/OBSBasicSettings.ui
 	forms/OBSBasicSourceSelect.ui
 	forms/OBSBasicInteraction.ui
+	forms/OBSExtraBrowsers.ui
 	forms/OBSUpdate.ui
 	forms/OBSRemux.ui
 	forms/OBSAbout.ui)