HttpSigningAuth.cs doesn't properly account for Encrypted Private Keys

[ThatWindowsGuy]

If you try to use the 'ApiKeyPassPhrase' parameter with the 'Set-IntersightConfiguration' cmdlet and an encrypted private key, it will never succeed whether you use the v2 (RSA) or v3 (EC) API.

When it parses the private key contents is it looking for headers and footers that will only match non-encrypted private keys.