build(vendor): migrate JUCE webkit2gtk from 4.0 to 4.1

Update all vendored JUCE 7.0.12 references from webkit2gtk-4.0 to
webkit2gtk-4.1: pkg-config targets, dynamic library names, docs, and
Projucer project exporter. The 4.0 API is removed in current Linux
distributions.

third_party/JUCE/modules/juce_gui_extra/juce_gui_extra.cpp

@@ -114,7 +114,7 @@
 #elif (JUCE_LINUX || JUCE_BSD) && JUCE_WEB_BROWSER
  JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wzero-as-null-pointer-constant", "-Wparentheses", "-Wdeprecated-declarations")
 
- // If you're missing this header, you need to install the webkit2gtk-4.0 package
+ // If you're missing this header, you need to install the webkit2gtk-4.1 package
  #include <gtk/gtk.h>
  #include <gtk/gtkx.h>
  #include <glib-unix.h>

third_party/JUCE/modules/juce_gui_extra/native/juce_WebBrowserComponent_linux.cpp

@@ -206,7 +206,7 @@ private:
     }
 
     //==============================================================================
-    DynamicLibrary gtkLib { "libgtk-3.so" }, webkitLib { "libwebkit2gtk-4.0.so" };
+    DynamicLibrary gtkLib { "libgtk-3.so" }, webkitLib { "libwebkit2gtk-4.1.so" };
     const bool webKitIsAvailable = loadWebkitSymbols() && loadGtkSymbols();
 
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (WebKitSymbols)