Implement a comprehensive mechanism to ensure correct C++ runtime
initialization before the kernel main function is called. This replaces
the previous, incomplete reliance on an `_init` function.

The new design robustly handles both legacy `.ctors` and modern
`.init_array` initialization schemes used by the GNU toolchain. A single
C++ function, `invoke_global_constructors`, now iterates through both
arrays of function pointers to ensure all types of global initializers
are executed.