Feature/revamp -- add new tables and fields

[fivetran-jamie]

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fivetran made PR

What change(s) does this PR introduce?

• adds new sources and documents them
• adds new staging tables and documents + tests them
• adds new fields to existing models. documentation of these new fields will happen in a later PR
• moved column macros to individual column macros (and delete the staging_columns.sql file). I will move the aliasing from the column macros to the model files in my next PR
• new seed data

[fivetran-reneeli]

Hi @fivetran-jamie wow lots of new tables! It looks good, just had some minor things:

• cast timestamps fields in staging models with dbt.type_timestamp (I recall this being included in our standardization updates so may as well follow it here)
• maybe update 'index' in the respective staging models to specify which model it's from? This is more if you think this field gets used downstream at some point, and there's so many models that the same field (customer_tag, abandoned_checkout_discount_code, order_shipping_tax_line, order_tag, product_tag)
• I noticed you added the union data feature to the tmp models, don't forget to add the source relation macro and column to staging models!

[fivetran-jamie]

ah yeah index won't really get used so i think we're good not renaming it. otherwise, added the source relation stuff and the timestamp casts! will also make sure to add the timestamp casts to the other models in my other PR

[fivetran-reneeli]

The timestamp updates and union data macro addition look good to go 👍