CertificateImport: add support for certificates import via HTTP(S)

[fullenw1]

Details of the scenario you tried and the problem that is occurring

Currently, the ImportCertificate only supports import of certificates with file shares.
However, for standalone computers this becomes complicated because you have to first create a share mapping which involves also the usage of credential.

Verbose logs showing the problem

PowerShell DSC resource MSFT_CertificateImport failed to execute Set-TargetResource functionality with error message: Certificate Pfx file 'https://FileServer/DscFileRepository/Certificates/certificate.crt' not found. (CI0006)

Suggested solution to the issue

The HTTP(S) download is already implemented in the File resource.
We could do the same by importing certificates downloaded via HTTP(S)

The DSC configuration that is used to reproduce the issue (as detailed as possible)

Datum configuration:

CertificateDsc:
  CertificateImport:
    - Path: https://FileServer/DscFileRepository/Certificates/certificate.crt
      Location: LocalMachine
      Store: My
      Ensure: Present
      FriendlyName: MyCertificate
      Thumbprint: 1C875AB1F29FC357E3F861FE1EF438E089053E2E

The operating system the target node is running

OsName               : Microsoft Windows Server 2019 Datacenter
OsOperatingSystemSKU : DatacenterServerEdition
OsArchitecture       : 64-bit
WindowsVersion       : 1809
WindowsBuildLabEx    : 17763.1.amd64fre.rs5_release.180914-1434
OsLanguage           : en-US
OsMuiLanguages       : {en-US}

Version and build of PowerShell the target node is running

Name                           Value
----                           -----
PSVersion                      5.1.17763.316
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.17763.316
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

Version of the DSC module that was used ('dev' if using current dev branch)

ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Manifest   4.7.0.0    CertificateDsc

[PlagueHO]

Hi @fullenw1 - It should be possible to modify this to detect the file source as HTTP/HTTPS and download the file locally before importing it.