[enhancement]: Support defining registry for downloading tfx-cli in TfxInstaller

[katydecorah]

Task name

TfxInstaller

Describe your feature request here

When TfxInstaller installs tfx-cli, it pulls from the public registry. Microsoft teams are required to use the central feed and not the public registry. If the TfxInstaller could accept a registry input, or parse the registory from the npmrc file, then this will unblock this effort.

My current workaround is to install tfx-cli while defining the private registory and then add a script to make sure the correct tfx path is set for PackageAzureDevOpsExtension task to find it.