cli: customer download-license --output flag shadows global --output format flag

[nvanthao]

Problem

The customer download-license command registers a local --output (short: -o) flag that specifies a file path for writing the downloaded license:

cmd.Flags().StringVarP(&output, "output", "o", "-", "Path to output license to. Defaults to stdout")

This shadows the global persistent --output flag (which controls output formatting: json|table|wide) introduced in #740.

Impact

Running:

replicated customer download-license --customer cus_xxx --output json

does not format the license as JSON. Instead, it writes the license YAML to a file literally named json.

This is confusing and inconsistent with every other command in the CLI.

Suggested Fix (non-breaking)

Deprecate the current --output / -o file-path flag and introduce a new flag for file output:

1. Add --path (or --output-file) as the new file-path destination flag.
2. Deprecate --output on this command (or remove its short form -o) so it falls through to the global --output persistent flag for formatting.
3. Consider whether JSON output is actually useful for a raw license YAML download.

Context

This was explicitly called out in review of #740 by @xavpaice and deferred to a follow-up PR to avoid making a breaking change in the global output flag refactoring.