Add australiaeast to allowed locations for OpenAI

[amul047]

Purpose

To add australiaeast to allowed locations for OpenAI - this is now generally available according to https://azure.microsoft.com/en-us/explore/global-infrastructure/products-by-region/?products=cognitive-services&regions=australia-central,australia-central-2,australia-east,australia-southeast

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

Run azd up and choose australiaeast