Iterate through canonical timezones and metazones

[robertbastian]

[robertbastian]

So I added this because you were convinced that there are use cases of iterating through all time zones or all metazones for displaying time zone pickers. Do you still think that's a use case? I can bit pack the data struct, we can store this information for free if we want.

If not, just close the PR.

[sffc]

I'm not convinced that this approach works

Did you consider when a time zone changes metazones, thereby messing up the mapping?

[robertbastian]

Did you consider when a time zone changes metazones, thereby messing up the mapping?

That's a CLDR problem, they define golden zones. But whatever

[sffc]

I'm pretty sure golden zones are not meant to be stable.

But, I'm fine closing this PR and revisiting something like this when we have someone asking for it.