bug: Unreachable code should fire a warning with diagnostics, not an error

[enitrat]

Bug Report

Cairo version:
2.7.1

Current behavior:
Unreachable code fires an error that prevents compilation. Consider emitting a warning that can be autofixed with cairo-lint down the line.

example:

fn main(){
 core::panic_with_felt252('hello world');
 let x  = 'cairo is cool';
 }