Enable V8 sandbox by default (fixes #3332)

When the V8 sandbox is enabled, ArrayBuffer backing stores must be
allocated inside the sandbox address space. This change introduces a new
CefV8Value::CreateArrayBufferWithCopy method that copies the memory
contents into the sandbox address space.

Enabling the V8 sandbox can have a performance impact, especially when
passing large ArrayBuffers from C++ code to the JS side. We have therefore
retained the old CefV8Value::CreateArrayBuffer method that references
external memory. However, this method can only be used if the V8 sandbox is
disabled at CEF/Chromium build time.

To disable the V8 sandbox add `v8_enable_sandbox=false` to
`GN_DEFINES` when building CEF/Chromium.

libcef_dll/wrapper/cef_message_router_utils.h

@@ -48,6 +48,7 @@ struct RendererMessage {
   std::variant<CefString, CefRefPtr<const CefBinaryBuffer>> payload;
 };
 
+#ifndef CEF_V8_ENABLE_SANDBOX
 class BinaryValueABRCallback final : public CefV8ArrayBufferReleaseCallback {
  public:
   explicit BinaryValueABRCallback(CefRefPtr<CefBinaryBuffer> value)
@@ -62,6 +63,7 @@ class BinaryValueABRCallback final : public CefV8ArrayBufferReleaseCallback {
 
   IMPLEMENT_REFCOUNTING(BinaryValueABRCallback);
 };
+#endif
 
 CefRefPtr<BrowserResponseBuilder> CreateBrowserResponseBuilder(
     size_t threshold,