LibGUI: Allow constructing a string Variant from StringView

Author: https://github.com/alimpfard
Commit: b072cb725f
Pull-request: https://github.com/SerenityOS/serenity/pull/5866
Issue: https://github.com/SerenityOS/serenity/issues/4269
Issue: https://github.com/SerenityOS/serenity/issues/4821
Issue: https://github.com/SerenityOS/serenity/issues/5550
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibGUI/Variant.cpp

@@ -143,6 +143,11 @@ Variant::Variant(const FlyString& value)
 {
 }
 
+Variant::Variant(const StringView& value)
+    : Variant(value.to_string())
+{
+}
+
 Variant::Variant(const String& value)
     : m_type(Type::String)
 {

Userland/Libraries/LibGUI/Variant.h

@@ -42,6 +42,7 @@ public:
     Variant(i64);
     Variant(unsigned);
     Variant(const char*);
+    Variant(const StringView&);
     Variant(const String&);
     Variant(const FlyString&);
     Variant(const Gfx::Bitmap&);