digest template updates (#3410)

## Summary
- remove Poppins font (wasn't rendering the font weight properly when in
between font weights in the provided files, might be a way around this
but it's not supported in a bunch of email clients anyway so removing it
for now)
- change tables to divs so `<a>` tag can span entire row
- add footer
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## How did you test this change?
- uploaded template to sendgrid and sent test email
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## Are there any deployment considerations?
- no, this is just to keep a record of the current template
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Author: mayberryzane