Make `Property<string>` convertible to `string_view`

This should work:

void f(std::string_view);
Gaudi::Property<std::string> prop{"abc"};
f(prop);

today we have to use f(prop.value()).

diff --git a/GaudiKernel/GaudiKernel/Property.h b/GaudiKernel/GaudiKernel/Property.h
index dcc0a7859..944fc204a 100644
--- a/GaudiKernel/GaudiKernel/Property.h
+++ b/GaudiKernel/GaudiKernel/Property.h
@@ -483,6 +483,12 @@ namespace Gaudi {
     //   return m_value;
     // }
 
+    template < typename Dummy = TYPE, typename = std::enable_if_t< std::is_constructible_v< std::string_view, Dummy > > >
+    operator std::string_view() const {
+      m_handlers.useReadHandler( *this );
+      return m_value;
+    }
+
     /// equality comparison
     template <class T>
     bool operator==( const T& other ) const {

???

mentioned in commit f26b44f1

mentioned in merge request !1002 (merged)

mentioned in commit 08c96df8

assigned to @graven

changed milestone to %v33r0

mentioned in commit 56189480

mentioned in commit 3814bfdd

mentioned in commit ac500329

closed via merge request !1002 (merged)

mentioned in commit b9b1aa54