CLDR-19122 add preferred zones

[robertbastian]

CLDR-19122

• This PR completes the ticket.

ALLOW_MANY_COMMITS=true

[macchiati]

Looking good so far.

[robertbastian]

I compiled this by generating a list of time zone -> metazone golden mappings for the same country, but as those also include zones that differ by DST, I manually checked all of them. It might be possible to make this fully algorithmic, but it would be a non-trivial algorithm, so I think it makes sense to hardcode them (and we can test against metazones if we want).

[macchiati]

I compiled this by generating a list of time zone -> metazone golden mappings for the same country, but as those also include zones that differ by DST, I manually checked all of them. It might be possible to make this fully algorithmic, but it would be a non-trivial algorithm, so I think it makes sense to hardcode them (and we can test against metazones if we want).

I think it would be a good idea to have tests for this; while there is some latitude, there should be some upper and lower bounds that can be tested for (and we'll have access to the tzdb)