use logging instead of prints (#499)

# What does this PR do?

This PR moves all print statements to use logging. Things changed:
- Had to add `await start_trace("sse_generator")` to server.py to
actually get tracing working. else was not seeing any logs
- If no telemetry provider is provided in the run.yaml, we will write to
stdout
- by default, the logs are going to be in JSON, but we expose an option
to configure to output in a human readable way.

llama_stack/providers/inline/inference/meta_reference/quantization/scripts/quantize_checkpoint.py

@@ -8,6 +8,7 @@
 # This software may be used and distributed in accordance with the terms of the Llama 3 Community License Agreement.
 
 import json
+import logging
 import os
 import shutil
 import sys
@@ -32,6 +33,8 @@ from llama_stack.providers.inline.inference.meta_reference.quantization.fp8_impl
     quantize_fp8,
 )
 
+log = logging.getLogger(__name__)
+
 
 def main(
     ckpt_dir: str,
@@ -102,7 +105,7 @@ def main(
         else:
             torch.set_default_tensor_type(torch.cuda.HalfTensor)
 
-        print(ckpt_path)
+        log.info(ckpt_path)
         assert (
             quantized_ckpt_dir is not None
         ), "QUantized checkpoint directory should not be None"