Add support for Gaudi::Property to fmtlib

With version 10 fmtlib got more picky and it's not possible anymore to fmt::format("{}", someProperty) does not work anymore.

With this MR I add a header that can be included when we need to pass a property to fmtlib.

It's not included by default to avoid unnecessary compilation overhead.

Note that there is a number of commits for backward compatibility that should be reverted when we can drop support for older versions of fmtlib or C++.