Fixed problem with IncludeInOutput not being specified (#1045) (#1046)

* Fixed static code analyzer issues reported in (#972)

* In case IncludeInOutput is not specified code should be generated.

---------

Co-authored-by: Jesper Glintborg <jesper.glintborg@siemensgamesa.com>

src/protobuf-net.BuildTools/Generators/ProtoFileGenerator.cs

@@ -152,7 +152,7 @@ void AddExtraPath(string? fragment)
                     }
 
                     bool includeInOutput = true;
-                    if (userOptions is not null && userOptions.TryGetValue(Literals.AdditionalFileMetadataPrefix + "IncludeInOutput", out var optionValue) && bool.TryParse(optionValue, out includeInOutput))
+                    if (userOptions is not null && userOptions.TryGetValue(Literals.AdditionalFileMetadataPrefix + "IncludeInOutput", out var optionValue) && !string.IsNullOrWhiteSpace(optionValue) && bool.TryParse(optionValue, out includeInOutput))
                     {
                         // Do nothing here as includeInOutput will be overwritten by .TryParse,
                         // if a value was successfully read and parsed.