[Feature Request] Enable using '-' as a filename to read from stdin

**Is your feature request related to a problem? Please describe.**
We're running a script to create and manage policies in a gitops way, but we're having to write each config to a temporary file to be able to create/update these.

**Describe the solution you'd like**
Almost all commandline tools that read files support using the '-' character as a special filename to indicate that it should read from stdin. This feature would enable us to pipe the object to the az commandline directly.

**Additional context**
For example: $policy | Convertto-Json -Depth 10 -Compress | az repos policy create --org $org --project $proj --config -