I find myself wanting the ability to point VPK to specific folders in my blob storage.
I like to keep separation by platform personally, but I also just want a "content" storage for packages, images, etc. I'd rather not make another blob storage just for these packages and have to set up another CDN, track more secrets, etc.

AI generated:

This change adds a --folder parameter to both 'vpk upload az' and 'vpk download az' commands, allowing users to organize releases in subdirectories within their Azure blob containers.

Key changes:

• Added Folder property to AzureUploadOptions and AzureDownloadOptions
• Modified AzureRepository to prepend folder paths to all blob operations
• Updated upload, download, and delete operations to work with folder paths
• Retention policy (--keepMaxReleases) correctly handles files in folders
• Release index and legacy release files are stored in the specified folder

Usage

This enables multiple applications or environments to share a single Azure container by using folders as isolated namespaces:

# Upload to a folder
vpk upload az --folder "releases/osx-x64" --account myaccount --key mykey --container mycontainer --releaseDir ./releases

# Download from a folder
vpk download az --folder "releases/osx-x64" --account myaccount --key mykey --container mycontainer

# UpdateManager configuration
var source = new SimpleWebSource("https://myaccount.blob.core.windows.net/mycontainer/releases/osx-x64/");

The implementation is backward compatible - existing deployments without folders continue to work as before.

Testing

• All existing tests pass
• Added comprehensive test coverage for folder functionality
• Build succeeds with 0 warnings, 0 errors