rename time.py to lftime.py to avoid stdlib collision

[NavidSassan]

this would prevent name collisions, for example with the in-built time library (see b812fae).

[markuslf]

Currently, the only actual collision with the Python standard library is time.py (see b812fae). All other modules (base, url, txt, shell, etc.) have no naming conflicts with stdlib.

Since the libraries are imported as a package (import lib.time, not import time), the collision only occurs in specific situations — e.g. when lib/ ends up directly on sys.path.

Renaming all ~35 modules would be a massive breaking change affecting every single plugin in the monitoring-plugins repo. For a single collision, that trade-off doesn't seem worth it.

We'll rename only the conflicting module (time.py → lftime.py). If more collisions arise in the future, we can revisit a broader renaming.