First name and last name not saved on user

[ijreilly]

When a user joins a workspace, we ask them for their first name and last name that we save in their workspaceMember, but not on the user.
This is problematic because, among probably other things, we use the user saved name to determine createdByName (cf CreatedByFromAuthContextService). Therefore createdByName is left empty and we will lose the creator information if a user leaves the workspace, as their workspaceMember will be deleted.

Several things to do here

1. Save first name and last name on user
2. Fix existing: Create and run a command to get name from workspaceMember on user, or in CreatedByFromAuthContextService default to workspaceMember name if userName is an empty string