Proj4027: Use valid diagnostic severity value

The .NET compiler requires standard severity keywords to parse global configuration files correctly. Using invalid values prevents the rule from being applied as intended.

It is worth pointing out that suggestion is being displayed as info and that silent is refered to as hidden.

Non-compliant

is_global = true
        
dotnet_diagnostic.IDE0002.severity = hidden
dotnet_diagnostic.IDE0004.severity = info
dotnet_diagnostic.IDE0005.severity = sugestion
dotnet_diagnostic.IDE0006.severity = warn

Compliant

is_global = true
        
dotnet_diagnostic.IDE0002.severity = silent
dotnet_diagnostic.IDE0004.severity = suggestion
dotnet_diagnostic.IDE0005.severity = suggestion
dotnet_diagnostic.IDE0006.severity = warning