[paulbalandan]

Description
Refactors the Hmac command:

• Removes property.nonObject errors
• Removes unnecessary $that = $this and $encrypter = $this->encrypter assigns by using a non-static closure
• The saving model is instantiated once per run, not per action

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[paulbalandan]

The second commit reduces the visibility of the action methods from public to private thus reaching 100% MSI. I believe this is fine as I don't think anyone would be calling this command programmatically like (new Hmac())->encrypt(). As such this is just potentially BC breaking with a low chance. Otherwise, please let me know and it can be reverted.