Feature request: Add region config to `default.global.parameters`

### Describe your idea/feature/enhancement

I wish SAM CLI would add the region configuration to `default.global.parameters` in the `samconfig.toml`.

Currently, when using `sam init´ the samconfig is generated based on the user input, and the only property in `default.global.parameters` is the stack_name. The region parameter is added under `default.deploy.parameters` which means that all `sam deploy` commands will use the specified region. However, `sam sync` uses the default region in the local installation of the AWS CLI configuration, which causes a lot of misstakes and deployments to the wrong region.

### Proposal

Add region to `default.global.parameters` to ensure all deployment using `sam sync` use the same configured region.

Things to consider:
1. Will this require any updates to the [SAM Spec](https://github.com/awslabs/serverless-application-model)
No.

### Additional Details