Invoke-RestMethod and Invoke-WebRequest don't support client certificate authentication with certificate files #4544
Description
Invoke-RestMethod and Invoke-WebRequest requires the certificate specified by -Certificate to be imported in the certificate store. Both methods do not allow using certificates from files. This breaks client certificate authentication on non-Windows platforms.
Proposal: Support the use of certificate files for the client authentication by adding a new parameter -CertificateFile or by using the x509 object from Get-PfxCertificate directly.
This was tested on Ubuntu 16.04 with PowerShell 6.0.0-beta.5 and on Windows with PowerShell 5.0.