CLI 0.0.14, Uvicorn update and no more [serve] (#12845)

Calls uvicorn directly from cli:
Reload works if you define app by import string instead of object.
(was doing subprocess in order to get reloading)

Version bump to 0.0.14

Remove the need for [serve] for simplicity.

Readmes are updated in #12847 to avoid cluttering this PR

libs/cli/langchain_cli/namespaces/app.py

@@ -220,8 +220,10 @@ def serve(
     """
 
     app_str = app if app is not None else "app.server:app"
-    port_str = str(port) if port is not None else "8000"
     host_str = host if host is not None else "127.0.0.1"
 
-    cmd = ["uvicorn", app_str, "--reload", "--port", port_str, "--host", host_str]
-    subprocess.run(cmd)
+    import uvicorn
+
+    uvicorn.run(
+        app_str, host=host_str, port=port if port is not None else 8000, reload=True
+    )