Set AWS region in config files instead of GitHub Actions variables

[pbobov]

Setting AWS region in config files:

1. Allows using different regions for different deployments, and
2. Prevents accidental deletion and recreation of ALL the resources if AWS_DEFAULT_REGION GitHub Actions variable is changed or deleted.

[pbobov]

The fix:

1. Adds aws_region input variable to all Terraform modules and Packer templates.
2. In GitHub actions workflows, sets aws_region input variable to the value of AWS_DEFAULT_REGION GitHub Actions variable.
3. In GitHub actions workflows, sets azure_region input variable to the value of AZURE_DEFAULT_REGION GitHub Actions variable.

This supports different deployments in different AWS/Azure regions, if required.at the same time, it does not require setting regions in each config file, when all the deployments are in the same region, which is the typical case.