Bring up new windows VMs & CI workflows

[h-vetinari]

In #145, we moved the build scripts for the windows VMs used on various feedstocks to this repo, a big milestone!

However, since the builds were starting from an empty image, a bunch of things did not work out of the box. I've fixed some of them iteratively, but when this didn't help, I broke them out into separate -ng images (#163) that can be iterated on without breaking all other feedstocks.

This issue is to track problems and their fixes

• Missing base packages
  • Add bash to windows images #151
  • add pwsh to windows images #153
  • 7z (e43623b, d9ccee2)
  • vcredist140 (84c7e8b); otherwise micromamba breaks
  • Add MSVC compilers #170
• path preparations
  • Ensure C:\bld exists in windows images #155
  • enable long paths (59ea8e3)
• Switch windows VM to East US region #158
  • should help with upload issues to Anaconda CDN
  • Failed attempts in change region to East US for win VM; add 7z & more paths #157, Reapply "change region to East US" #165
• ensure CI fails when image fails to build
• run packer build in PRs?
• test that package uploads work end-to-end
  • test new windows images end-to-end llvmdev-feedstock#362

[aktech]

Enabled the OIDC creds to work on PRs:

APP_OBJECT_ID=$(az ad app show --id $WINDOWS_CI_AZURE_CLIENT_ID --query id -o tsv)
az ad app federated-credential create --id $APP_OBJECT_ID --parameters '{
    "name": "github-pr",
    "issuer": "https://token.actions.githubusercontent.com/",
    "subject": "repo:conda-forge/.cirun:pull_request",
    "audiences": ["api://AzureADTokenExchange"]
  }'
{
  "@odata.context": "https://graph.microsoft.com/v1.0/$metadata#applications('bbeefbf3-6e0a-4ef2-aeca-ab7820d6ecb0')/federatedIdentityCredentials/$entity",
  "audiences": [
    "api://AzureADTokenExchange"
  ],
  "description": null,
  "id": "636b8662-f45c-4bc0-bcad-7f12c4cf5685",
  "issuer": "https://token.actions.githubusercontent.com/",
  "name": "github-pr",
  "subject": "repo:conda-forge/.cirun:pull_request"
}