fix(signal): intercept delivery via dequeue

[lacraig2]

This pull request refactors the signal hooking mechanism in signal_hc.c to use a kretprobe on dequeue_signal instead of a kprobe on __send_signal. This change improves compatibility with newer Linux kernels and provides more reliable signal interception. The code now tracks the relevant task_struct across function entry and return, and updates how signal suppression is performed.

Signal hooking mechanism refactor:

• Replaces the use of a kprobe on __send_signal with a kretprobe on dequeue_signal, updating initialization and handler logic to match the new probe type. [1] [2]
• Introduces the signal_probe_data struct to pass the task_struct between entry and return handlers, ensuring accurate context for signal processing. [1] [2]
• Updates the handlers to retrieve the signal number from the function return value and the task from the probe data, improving accuracy and kernel compatibility.
• Changes the method for silencing signals: instead of modifying a syscall argument, it now sets the return value directly using igloo_regs_set_return_value.
• Adds a kernel version check to ensure compatibility with kernel versions 5.0.0 and above when capturing the current task. [1] [2]