different func type args take different values for the same thing

[dprotaso]

I noticed that when using func init we pass in -t cloudevents but when using func invoke the -f=cloudevent

I understand the difference but it would be nice to use cloudevents/cloudevent interchangeably. This reduces the cognitive load of the user.

[dprotaso]

I would suggest we advertise a single casing but accept both casing for backwards compatability