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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`

<!--- HINT: You can also paste gist.github.com links for larger files -->

'2.23.42.0.48': ('setct-CertInqReqTBS', ),
    '2.23.42.0.49': ('setct-ErrorTBS', ),
    '2.23.42.0.50': ('setct-PIDualSignedTBE', ),
    '2.23.42.0.51': ('setct-PIUnsignedTBE', ),
    '2.23.42.0.52': ('setct-AuthReqTBE', ),
    '2.23.42.0.53': ('setct-AuthResTBE', ),
    '2.23.42.0.54': ('setct-AuthResTBEX', ),
    '2.23.42.0.55': ('setct-AuthTokenTBE', ),
    '2.23.42.0.56': ('setct-CapTokenTBE', ),
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    '2.23.42.0.58': ('setct-AcqCardCodeMsgTBE', ),
    '2.23.42.0.59': ('setct-AuthRevReqTBE', ),
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    '2.23.42.0.77': ('setct-CertReqTBE', ),