[Bugfix]: Shell runtime execution with security context

[quaark]

Shell runtime would need to chmod the run script to give it execute permissions.
If a security context is given, this fails.

Added a check to see if the handler is a script in the current working directory or a command from the PATH.
If it is a command, it is run with sh -c
If not, it is run with sh (without -c) which results in sh reading the file as a script and running it, so there's no need to chmod the file.

Benchmarked the changes in the event processing function to ensure no large loss of performance happens because of the string manipulations. The performance change is negligible.

[liranbg]

Looking good and great addition!

some comment below, most important is that when changing delicate code in event processing, we must ensure the changes aligned / improving performance and not hurting them for stylish changes