* aws_ec2 Implement the missing 'region discovery' (#51333)
* aws_ec2 Implement the missing 'region discovery'
fixes#45288
tries to use api as documented (which seems to fail in latest boto3 versions)
and fallback to boto3 'hardcoded' list of regions
* fixes and cleanup, add error for worst case scenario
* fix tests, remove more unused code
* add load_name
* acually load the plugin
* set plugin as required
* reverted test changes, removed options tests
* fixes as per feedback and cleanup
* Allow default regions list to use flexible credential types
