add --version to llama stack CLI & /version endpoint (#732)

# What does this PR do?

- add --version to llama stack CLI 
- add /version endpoint
- run OpenAPI generator for the new endpoint

## Test Plan

**CLI**
<img width="184" alt="image"
src="https://github.com/user-attachments/assets/3acb1d22-453e-4b79-baf6-e98e88d0671c"
/>



**endpoint**
<img width="430" alt="image"
src="https://github.com/user-attachments/assets/79cdd670-493b-40cf-8f9e-28a4ac0988ac"
/>


## Sources

Please link relevant resources if necessary.


## Before submitting

- [ ] This PR fixes a typo or improves the docs (you can dismiss the
other checks if that's the case).
- [ ] Ran pre-commit to handle lint / formatting issues.
- [ ] Read the [contributor
guideline](https://github.com/meta-llama/llama-stack/blob/main/CONTRIBUTING.md),
      Pull Request section?
- [ ] Updated relevant documentation.
- [ ] Wrote necessary unit or integration tests.

llama_stack/cli/stack/stack.py

@@ -5,6 +5,7 @@
 # the root directory of this source tree.
 
 import argparse
+from importlib.metadata import version
 
 from llama_stack.cli.subcommand import Subcommand
 
@@ -24,6 +25,12 @@ class StackParser(Subcommand):
             description="Operations for the Llama Stack / Distributions",
         )
 
+        self.parser.add_argument(
+            "--version",
+            action="version",
+            version=f"{version('llama-stack')}",
+        )
+
         subparsers = self.parser.add_subparsers(title="stack_subcommands")
 
         # Add sub-commands