feat: llama stack show

`llama stack show` prints all required pip dependencies. It does this by using the `module` in the provider spec as the installation directory and gets all deps using the new `pyproject.toml`, providers can be installed as a package using the dependencies in the pyproject

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

llama_stack/cli/stack/show.py

@@ -0,0 +1,69 @@
+# 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
+import textwrap
+
+from llama_stack.cli.stack.utils import ImageType
+from llama_stack.cli.subcommand import Subcommand
+
+
+class StackShow(Subcommand):
+    def __init__(self, subparsers: argparse._SubParsersAction):
+        super().__init__()
+        self.parser = subparsers.add_parser(
+            "show",
+            prog="llama stack show",
+            description="show the dependencies for a llama stack distribution",
+            formatter_class=argparse.ArgumentDefaultsHelpFormatter,
+        )
+        self._add_arguments()
+        self.parser.set_defaults(func=self._run_stack_show_command)
+
+    def _add_arguments(self):
+        self.parser.add_argument(
+            "--config",
+            type=str,
+            default=None,
+            help="Path to a config file to use for the build. You can find example configs in llama_stack/distributions/**/build.yaml. If this argument is not provided, you will be prompted to enter information interactively",
+        )
+
+        self.parser.add_argument(
+            "--distro",
+            type=str,
+            default=None,
+            help="Name of the distro config to use for show. You may use `llama stack show --list-distros` to check out the available distros",
+        )
+
+        self.parser.add_argument(
+            "--list-distros",
+            action="store_true",
+            default=False,
+            help="Show the available templates for building a Llama Stack distribution",
+        )
+
+        self.parser.add_argument(
+            "--env-name",
+            type=str,
+            help=textwrap.dedent(
+                f"""[for image-type={"|".join(e.value for e in ImageType)}] Name of the conda or virtual environment to use for
+the build. If not specified, currently active environment will be used if found.
+            """
+            ),
+            default=None,
+        )
+        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.",
+        )
+
+    def _run_stack_show_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 ._show import run_stack_show_command
+
+        return run_stack_show_command(args)