Allow for geographies to exist between meta and seed geographies

[JoeJimFlood]

As it currently stands, there is an implicit assumption in the code that the seed geography will be one level below the meta geography in the hierarchy. The CDOT implementation needs a geography in between the two. This pull request allows for any number of geographies in between the meta and seed geographies.

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[nick-fournier]

Hi @JoeJimFlood this is great, I can take a closer look but a couple of things off the top of my head:

• I want to write some unit tests to confirm it works, and locks in those gains.
• I want to also make sure it doesn't mess with downstream summary outputs. I remember there was an issue where it doesn't like when you request the zone totals for a zone above the smallest zone. Need to track down that issue.

If you can tackle the first one before I can get to this PR, it would definitely expedite things!

[JoeJimFlood]

@nick-fournier Thanks for reviewing it! I actually had already agreed to write a unit test, though figuring out exactly how has been a challenge. Right now I'm leaning towards running the CALM example with and without a geography in between the District and PUMA levels and checking that the outputs are the same.