feat: llama stack list-deps

`llama stack show` prints all required pip dependencies for a distro.
use --format to get different types of output (json, plain, deps-only). Users can pipe this output to the installation method of their choice: uv, pip install, etc

Signed-off-by: Charlie Doern <cdoern@redhat.com>

llama_stack/cli/stack/list_deps.py

@@ -0,0 +1,51 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+import argparse
+
+from llama_stack.cli.subcommand import Subcommand
+
+
+class StackListDeps(Subcommand):
+    def __init__(self, subparsers: argparse._SubParsersAction):
+        super().__init__()
+        self.parser = subparsers.add_parser(
+            "list-deps",
+            prog="llama stack list-deps",
+            description="list the dependencies for a llama stack distribution",
+            formatter_class=argparse.ArgumentDefaultsHelpFormatter,
+        )
+        self._add_arguments()
+        self.parser.set_defaults(func=self._run_stack_list_deps_command)
+
+    def _add_arguments(self):
+        self.parser.add_argument(
+            "config",
+            type=str,
+            nargs="?",  # Make it optional
+            metavar="config | distro",
+            help="Path to config file to use or name of known distro (llama stack list for a list).",
+        )
+
+        self.parser.add_argument(
+            "--providers",
+            type=str,
+            default=None,
+            help="sync dependencies for a list of providers and only those providers. This list is formatted like: api1=provider1,api2=provider2. Where there can be multiple providers per API.",
+        )
+        self.parser.add_argument(
+            "--format",
+            type=str,
+            choices=["uv", "deps-only"],
+            default="deps-only",
+            help="Output format: 'uv' shows shell commands, 'deps-only' shows just the list of dependencies without `uv` (default)",
+        )
+
+    def _run_stack_list_deps_command(self, args: argparse.Namespace) -> None:
+        # always keep implementation completely silo-ed away from CLI so CLI
+        # can be fast to load and reduces dependencies
+        from ._list_deps import run_stack_list_deps_command
+
+        return run_stack_list_deps_command(args)