Add Guard.IsDefined<TEnum>(...) (and maybe more enum related features)

[benjamin-hejl]

Hello, I am starting to use CommunityToolkit.Diagnostics, mainly the Guard and ThrowHelper classes but I have noticed lack of enum related checks. Among other things there could be methods like:

Guard.IsDefined<TEnum>(TEnum value, ...)
Guard.HasFlag<TEnum>(TEnum value, TEnum flag, ...)
Guard.IsAnyOf<TEnum>(TEnum value, params TEnum[] ...)
Guard.IsNoneOf<TEnum>(TEnum value, params TEnum[] ...)

I should be able to implement this feature.

[michael-hawker]

FYI @Sergio0694 transferred from WCT discussions. Seems like a nice idea.

@benjamin-hejl what would IsDefined do? Wouldn't that be by construction as enums are strongly-typed?

Do you have any usage patterns from examples of APIs you're trying to guard currently?

[benjamin-hejl]

It would forward call to Enum.IsDefined<TEnum>(value).

As for usage, I have a struct wrapper around Int64 with getters which interprets parts of the value as enums using shifts and bit masking. Methods using this struct should check that the values are correct.