Add full pwsh7 compatibility

[breakwaterlabs]

Powershell 7 does not support -encoding byte on add/get content. Instead it uses the 'asbytestream' switch.

This uses parameter splatting to convert all references to add- and get-content to be compatible regardless of powershell version.

PR Summary

PR Context

[breakwaterlabs]

@microsoft-github-policy-service agree