Add Stripe-Request-Trigger header

[xavdid-stripe]

Why?

We're working on surfacing more information to users around what their integration does when handling events. The first step of this is to tie subsequent API requests to the act of event processing. This PR adds a header to do just that.

There's some messiness here between headers and additionalHeaders, but it's not a thing we need to fix this second. I also fixed a bug with additionalHeaders that would have overridden auth headers (which makes me think no one has been using it)

What?

• add prepare recipe to justfile to aid automation
• add Stripe-Request-Trigger header in event helpers
• fix up a bug with rawRequest's additionalHeaders
• update node version (so it matches codegen; we didn't do it last oct)

See Also

• DEVSDK-3012