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##### SUMMARY
Allow to specify a new "format" parameter in "openssl_privatekey". Today the output format is decided by a very simple heuristic which requires further commands to work properly.
I need, for example, to generate a RSA private key but in PKCS8 format. The current heuristic uses OpenSSH format for RSA keys and only uses PKCS8 for Ed25519 and similar. This makes me use a "command" with "openssl" to convert the generated key, which leads to idempotency problems and unnecessary complexity.

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
openssl_privatekey

##### ADDITIONAL INFORMATION
<!--- Describe how the feature would be used, why it is needed and what it would solve -->
The current heuristic should be kept unless overwritten by user.

<!--- Paste example playbooks or commands between quotes below -->
```yaml
openssl_privatekey:
  path: /etc/ssl/private/ansible.com.pem
  format: pkcs8
```
The values allowed are `pkcs1`, `raw` and `pkcs8`

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try:
        import cryptography.hazmat.primitives.asymmetric.x25519
        CRYPTOGRAPHY_HAS_X25519 = True
        try:
            cryptography.hazmat.primitives.asymmetric.x25519.X25519PrivateKey.private_bytes
            CRYPTOGRAPHY_HAS_X25519_FULL = True
        except AttributeError:
            CRYPTOGRAPHY_HAS_X25519_FULL = False
    except ImportError:
        CRYPTOGRAPHY_HAS_X25519 = False
        CRYPTOGRAPHY_HAS_X25519_FULL = False
    try:
        import cryptography.hazmat.primitives.asymmetric.x448
        CRYPTOGRAPHY_HAS_X448 = True
    except ImportError:
        CRYPTOGRAPHY_HAS_X448 = False
    try:
        import cryptography.hazmat.primitives.asymmetric.ed25519
        CRYPTOGRAPHY_HAS_ED25519 = True
    except ImportError:
        CRYPTOGRAPHY_HAS_ED25519 = False
    try:
        import cryptography.hazmat.primitives.asymmetric.ed448
        CRYPTOGRAPHY_HAS_ED448 = True
    except ImportError:
        CRYPTOGRAPHY_HAS_ED448 = False
from ansible.module_utils import crypto as crypto_utils
from ansible.module_utils._text import to_native, to_bytes
from ansible.module_utils.basic import AnsibleModule, missing_required_lib
class PrivateKeyError(crypto_utils.OpenSSLObjectError):