[SIS] Allow "invited" as enrollment Status for SIS Import

[kellycronew]

Problem statement:

We would like to use the status of "invited" when enrolling via SIS Import file so that the user is not silently enrolled in the course but will see the Invite at the top of Canvas.

Proposed solution:

Similar to the API post for creating an enrollment, add the option to pass "invited" as an enrollment status.

User role(s):

admin