fix(pwsh): fix reading .pem files from PowerShell runspace

[thenextman]

When we call Encoding.GetString(byte[]) from a C# PowerShell runspace (e.g. DPS Console), we are getting the following error:

The following exception occurred while retrieving member "GetString": "GenericArguments[0], 'System.ReadOnlySpan1[System.Byte]', on 'System.Func2[T,TResult]' violates the constraint of type 'T'."

I don't know why. This results in an empty $PemData which obviously can't be parsed.

The workaround is to read the certificate and private key file directly as UTF8, rather than getting the UTF8 representation of the data.

[CBenoit]

Subtle! Thank you!