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/distribution/utils/exec.py

@@ -5,6 +5,7 @@
 # the root directory of this source tree.
 
 import errno
+import logging
 import os
 import pty
 import select
@@ -13,7 +14,7 @@ import subprocess
 import sys
 import termios
 
-from termcolor import cprint
+log = logging.getLogger(__name__)
 
 
 # run a command in a pseudo-terminal, with interrupt handling,
@@ -29,7 +30,7 @@ def run_with_pty(command):
     def sigint_handler(signum, frame):
         nonlocal ctrl_c_pressed
         ctrl_c_pressed = True
-        cprint("\nCtrl-C detected. Aborting...", "white", attrs=["bold"])
+        log.info("\nCtrl-C detected. Aborting...")
 
     try:
         # Set up the signal handler
@@ -100,6 +101,6 @@ def run_command(command):
     process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
     output, error = process.communicate()
     if process.returncode != 0:
-        print(f"Error: {error.decode('utf-8')}")
+        log.error(f"Error: {error.decode('utf-8')}")
         sys.exit(1)
     return output.decode("utf-8")