Support for ca-central-1 Region (Canada-Montreal)

**Community Note**
* Please vote on this issue by adding a 👍 reaction to the original issue to help the community and maintainers prioritize this request
* Please do not leave "+1" or "me too" comments, they generate extra noise for issue followers and do * not help prioritize the request
If you are interested in working on this issue or have submitted a pull request, please leave a comment

**Tell us about your request**
I would like to use App Runner in the ca-central-1 (Canada-Montreal) region.

**Describe alternatives you've considered**
We are looking at EKS and ECS options as well, but inclined towards AppRunner as it removes a lot of heavy lifting compared to the other options.

**Additional context**
We couldn't go out of ca-central-1 region due to data residency compliance. Hence eagerly looking for this service in Canada.