Uploadcare CLI: file download command

The CLI can now download files from the Uploadcare CDN to the local filesystem.

# Download a single file
uploadcare file download <uuid> --output ./photo.jpg
# Mirror all stored files into ./backup with 8 parallel workers
uploadcare file list --page-all --stored true --json uuid \
| uploadcare file download --from-stdin --output-dir ./backup --parallel 8

Supports streaming to stdout, batch downloads with templated filenames (${uuid}, ${filename}, ${ext}, ${effects}), CDN effects on images, concurrent downloads, progress reporting, and --dry-run.

See the file download reference for the full flag list.