Ladybird: Ensure that installed ladybird can launch WebContent process

Always call platform_init after there's a QApplication, because in the
installed configuration that's how we find the resources.

Try QCoreApplication::applicationDirPath() after looking in ./WebContent
for the WebContent process. In an installed configuration, ladybird and
WebContent will both be in $PREFIX/bin.

Add install rules for WebContent and its linked libraries, for if they
ever differ from ladybird's.

Ladybird/WebContent/CMakeLists.txt

@@ -1,10 +1,10 @@
 set(WEBCONTENT_SOURCE_DIR ${SERENITY_SOURCE_DIR}/Userland/Services/WebContent/)
 
 set(WEBCONTENT_SOURCES
-    ${WEBCONTENT_SOURCE_DIR}/ConnectionFromClient.cpp    
-    ${WEBCONTENT_SOURCE_DIR}/ConsoleGlobalObject.cpp    
-    ${WEBCONTENT_SOURCE_DIR}/PageHost.cpp    
-    ${WEBCONTENT_SOURCE_DIR}/WebContentConsoleClient.cpp    
+    ${WEBCONTENT_SOURCE_DIR}/ConnectionFromClient.cpp
+    ${WEBCONTENT_SOURCE_DIR}/ConsoleGlobalObject.cpp
+    ${WEBCONTENT_SOURCE_DIR}/PageHost.cpp
+    ${WEBCONTENT_SOURCE_DIR}/WebContentConsoleClient.cpp
     ../EventLoopPluginQt.cpp
     ../FontPluginQt.cpp
     ../ImageCodecPluginLadybird.cpp
@@ -14,7 +14,7 @@ set(WEBCONTENT_SOURCES
     ../WebSocketClientManagerLadybird.cpp
     ../WebSocketLadybird.cpp
     main.cpp
-)    
+)
 
 qt_add_executable(WebContent ${WEBCONTENT_SOURCES})
 

Ladybird/WebContent/main.cpp

@@ -38,10 +38,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     // FIXME: Refactor things so we can get rid of this somehow.
     Core::EventLoop event_loop;
 
-    platform_init();
-
     QGuiApplication app(arguments.argc, arguments.argv);
 
+    platform_init();
+
     Web::Platform::EventLoopPlugin::install(*new Ladybird::EventLoopPluginQt);
     Web::Platform::ImageCodecPlugin::install(*new Ladybird::ImageCodecPluginLadybird);