Add nom-supreme as a (feature-gated) first-class citizen

[Ben-PH]

I would like to feature-gate a re-export of nom-supreme.

• I consider ErrorTree as "the basic very-verbose" error in a minimilist/informative/very-verbose. in-crate Error and VerboseError make up the other two "basics"
• It signals to users that nom isn't meant to be a fully fleshed out utility. Its intent is to make the process of assembling different utilities together.
• It creates a better UX, in that users have the option of a heavy-weight, feature-rich experience.

I searched supreme in the issue searcher (not filtering by pr or issue), and nothing came up in the titles. Either this is a new thing (great), but if not, the discussion that follows will document the reasoning behind what's done for future contributors.