Use a html DSL for generating chart display files

[kMutagene]

This makes the html scaffolds more flexible and easier to maintain.

Issues such as #72 show how diverse the types of requirements can be for the html scaffold to change.

Best contender is Giraffe.ViewEngine using the HTML renderer functionality

Note that this is currently blocked because we can't yet support .NET 5.0

[kMutagene]

related: giraffe-fsharp/Giraffe.ViewEngine#14