Allow wildcard in AllowedReferenceRelatedFileExtensions

https://github.com/Microsoft/msbuild/blob/b630e674c729787d57a485ef5338915643eb1cea/src/Tasks/AssemblyDependency/ReferenceTable.cs#L873

When it comes to copying configuration files of referenced projects into the final output directory (of a solution's startup project), it would be nice if the startup project didn't need to list every possible configuration file extension that it needs to look for explicitly (such as `.development.json`, `production.json`, etc.). It would be much nicer to be able to write `.*.json` instead. Or just `.*` instead of `.json;.xml;.yml`, in the case that you don't want the project to be picky about what kind of config that it accepts. The same goes for files other than configuration.

This wouldn't be an issue if setting the config file properties to "copy always" did the trick, but this only works if the referenced project needs building. If it doesn't need building, then the build for the startup project will just skip it altogether and the config file doesn't get copied into the final output directory.