chore: import upstream snapshot with attribution

llm/default_plugins/default_tools.py

@@ -0,0 +1,8 @@
+import llm
+from llm.tools import llm_time, llm_version
+
+
+@llm.hookimpl
+def register_tools(register):
+    register(llm_version)
+    register(llm_time)