Add userId to Metadata

[leite08]

Ticket: https://github.com/metriport/metriport-internal/issues/43

Add userId to Metadata, so the webhook payload can identify which user the data refers to.

This only changes the data package.

Release plan

• Release this to NPN (minor version)
• Merge master back into develop
• Update the next feature branch of Update docs + mobile examples #43 to refer to the new data package version from NPM
  • Heads up: this will break existing mappings and require change on how we convert data into the shared data package

[Orta21]

When you say userid are you referring to the connected_user id right? Should we make this optional? Id not we need to make sure to update all of our mappings

[leite08]

As discussed internally, we're taking a diff approach to specifying the Customer/Account's userId in the webhook payload, so I'm closing this PR and feature branch.