I have changed the ApplySyntaxHighlighting so that Markdig no longer …

[sflanders95]

…innapropriately does not apply a <pre> block to language names not known to the ColorCode project. I also made it optional so users can opt out of not getting the expected results of a ``` block rendering in a <pre> tag"

note some of the properties may need to change back from public string Id => "default"; to public string Id { {get return "default"; } } or similar...

This is kind of a hack as I believe markdig does not handle ```unknownlang correctly as it renders the text in a ``` section as <div and not <pre. This hack simply fixes that.