[Website Feature]: Migrate Firebase Functions

[andrashee]

In the website repository, we have a bunch of backend / etl functions. As a next step, I would like to

• migrate them from vanilla javascript to typescript
• migrate them into this public repository

[ssandino]

@andrashee seems to be done, right?

[andrashee]

No, there are still quite some missing.

[ssandino]

@andrashee, I believe we can close this issue. It seems that some functions related to confirmation/payment emails weren't transferred to the new repo. We can address these with individual issues moving forward, instead of keeping this general one open.