Daemon mode

[kxxt]

From the beginning, tracexec is implemented as a troubleshooting tool that isn't designed to run for a long time.

• It keeps all the events in memory and does not release them.
• The usage of hash map of ArcStr for string de-duplication also cannot release unused strings due to lack of week variant of ArcStr

It might be useful to run tracexec in daemon mode to continuously collect exec events.
To achieve that, we need to

• Replace hashmap of ArcStr with a string interning library.
• Implement daemon mode and add a systemd service