Implement command-line support for provider obfuscation in Podman Machine init. This will allow users to initialize machines without needing to explicitly specify the provider, with the system automatically selecting the appropriate default provider for the platform.

The --provider flag will be added to allow users to create podman machines on different providers without needing to set or change the default provider. For example, on macOS where the default provider is libkrun, users can use --provider to create a machine using the applehv provider instead.

Command to be updated for provider obfuscation:

• podman machine init

Acceptance Criteria:
1. podman machine init will still create a machine based on the default provider
2. The --provider flag allows users to override the default provider selection
3. Error handling is consistent when initialization fails
4. Documentation is updated to reflect provider-agnostic usage and the --provider override option
5. New end to end tests are created for platforms that have multiple providers