fix(generate-config): update success message and default path for env

[rkpattnaik780]

This is a follow up to #1588 .

The PR updates the success message printed after configs are generated.
rhoas generate-config --type env should save configurations to rhoas.env

Verification Steps

1. Run the following command:

./rhoas generate-config --type env

2. The command should save configurations in rhoas.env.

Configurations successfully saved to "/home/rkpattnaik780/coding/redhat/mk/cli/rhoas.env"

You can now use existing service accounts or create new to connect to the services.
To create new service account, run this command:

  $ rhoas service-account create

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation change
• Other (please specify)

[wtrocki]

I would personally go with config.env but rhoas.env is ok.