Add version prefix to tokens

[srambach]

We'll want to version the tokens for coordinating any breaking changes with core. Version will be a design-tokens version, not the core version. (However, we will have a mapping of what versions work together, e.g. design-tokens v1 works with core v6)

[mcoker]

Notes from a discussion with @nicolethoen @srambach

The proposed plan is currently:

• Since we technically won't need a version in the token string until we need to implement a new version, we're going to hold off on adding a version for the time being, and when we need to add a new version, we'll start at v2
• Implied above with v2 and the issue description, but we confirmed the token version does not need to match the version of PF component classes/vars. Eg, maybe PF-v6/v7/v8 all use --pf-t--global if there are no breaking changes to tokens, and PF-v9 uses --pf-t--v2--global
  • Random related point, we're thinking that (for the most part) a breaking change to tokens will necessitate a breaking change to anything that consumes tokens, but breaking changes to things that consume tokens do not need to cause a breaking change in tokens or otherwise need to iterate/change token versions.
• Consider a unique version identifier in the string other than v[n] for token versions, to make it clear it's not the same as or tied to a major version of PF. Eg, something like --pf-t-2--global
• We can reconvene on the entire approach after v6/tokens release and we learn more about stuff like how they're used, what kinds of changes we're wanting to make to tokens,