this fixes an issue where using multiple powershell sessions with a
different Azure context would display the same context everywhere when
using Set-AzContext to switch between them
BREAKING CHANGE: this requires adding `$env:POSH_AZURE_ENABLED = $true`
to your PowerShell profile if you want to get the correct context
displayed in your prompt for Azure powershell
BREAKING CHANGE: this removes the posh-git segment. To mitigate,
rename the posh-git segment to git.
In case you had a custom template, make sure to migrate to the git
segment's template. You can now also leverage the same logic and
properties as the git segment in both the text template and/or
color templates.