Cast core stage data types

[thutuva]

Describe your changes

Please include a summary of any changes.

• added cross database macro to cast columes as dates
• casted tables before core union

How has this been tested?

Please describe the tests you ran to verify your changes. Provide instructions or code to reproduce output.

• dbt run finishes successfully

Reviewer focus

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n/a

Checklist before requesting a review

• I have updated the version number in dbt_project.yml file to reflect the release number of this PR
• I have updated the docs files (by running dbt docs generate/serve and copying the necessary files into the docs folder)
• I have commented my code as necessary
• I have added at least one Github label to this PR
• My code follows style guidelines
• (Optional) I have recorded a Loom to explain this PR

(Optional) Gif of how this PR makes you feel

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[tuvaforrest]

looks good to me