Refactor update process execution and signaling

[devtekve]

Changed update process execution from a Python to a native process. Updated signal-based process control to match new process configurations.

Description

https://github.com/commaai/openpilot/pull/32716 removed the process title, which meant that we could no longer send signals to it as we used to which caused this issue https://github.com/commaai/openpilot/issues/32881.

Following recommendations here https://github.com/commaai/openpilot/pull/32716#issuecomment-2166919909, we are updating it to be a native process and update the signal sent from software_settings

Verification

Installed this branch on my devices and clicked the update button and I saw on the logs the signal was received.