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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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__metaclass__ = type
import sys
from distutils.version import LooseVersion
try:
    import OpenSSL
    from OpenSSL import crypto
except ImportError:
    
    
    pass
try:
    import cryptography
    from cryptography import x509
    from cryptography.hazmat.backends import default_backend as cryptography_backend
    from cryptography.hazmat.primitives.serialization import load_pem_private_key
    from cryptography.hazmat.primitives import hashes
    import ipaddress
    
    
    
    
    
    
    
    if LooseVersion(cryptography.__version__) < LooseVersion('2.1'):
        
        
        
        
        def simple_hash(self):