Extensions enhancement - IsZipCode() method added

The .IsZipCode() method was added to both the System.String and System.Text.StringBuilder objects.  It allows the developer the ability to quickly check if a string is in valid US zip code format e.g.

"12345".IsZipCode()

will return True as will

"12345-6789".IsZipCode()

but this

"12345678".IsZipCode()

Will return False.

For a more detail of what Extensions offer, see:

README page on GitHub - https://github.com/cjvandyk/Quix/blob/master/Extensions/README.md

NuGet as Extensions.cs - https://www.nuget.org/packages/Extensions.cs/2.0.1

GitHub Source - https://github.com/cjvandyk/Quix/blob/master/Extensions

Gitter - https://gitter.im/ExtensionsCS/Extensions

Discord - https://discord.com/channels/799027565465305088/799027565993394219

Suggestions and bugs - https://github.com/cjvandyk/Quix/discussions

Add Extensions to your toolbox and make your coding life a little easier.  

Happy coding

C