Warning Message needed for COE with offerings under Change awaiting approval

**Describe the task**
As an _institution user_, _I want_ to have a clear warning message at the top of the Confirm Enrolment screen _so that_ when I'm reviewing a student where an offering is under "Change awaiting approval" status I either go review the offering, wait for offering to be updated or continue with COE.

I may only be handling the COE queue today and not reviewing the Programs/Offerings before I COE a student. I won't know that there is a change under review which could impact the student funding.

For both public and private (PIR) offerings

**Acceptance Criteria**
- [ ] Warning banner/message to be displayed at the top of the page to show that the student offering is under review
- [ ] Content of banner message (TBD) "Warning: Offering is under Change awaiting approval. Please review the offering before proceeding."
- [ ] Add "Change Awaiting approval" status beside the offering name on the review page (TBD)

Start at the Confirm Enrolment screen and review page described in the issue, then trace how the offering status and offering name are presented for public and private (PIR) offerings. Done means the review shows the requested warning and the “Change awaiting approval” status beside the offering name, with the final banner wording confirmed.

Written by the indexing model from the issue text.