Because:
* Firefox always creates a Sync-scoped access token even when the user is not using Sync, impacting DAU
* Our grant types always create an access token when a refresh token is created. This is standard oauth, but because Firefox does not immediately need and use the access token given back for fxa-credentials and authorization_code grants, we need to either suppress the access token creation, or suppress the DAU event
* Because it is standard oauth to always return an access token, and because doing something non-standard will add another wrinkle to moving to an oauth standard library later, and because we already have at least one other separate case where we want to suppress a DAU event (FXA-14159), we want to continue creating the access tokens and logging access token created events
This commit:
* Adds a new "oauth token created DAU" Glean event that fires near the previous DAU measurement event, oauth access token created
* Adds a suppress_dau option for fxa-credentials and authorization_code oauth token grants so that when passed, we still emit the access token created event, but we suppress the new event
closes FXA-14206