[Feature] KernelSU flashable injector for unsupported stock kernel

[Nixsuki]

Is your feature request related to a problem? Please describe.

Hi, I wanted to know if possible to add a flashable injector to stock kernel on unsupported kernels?

Describe the solution you'd like.

Solution is to be universally use KernelSU for all stock kernels and CustomROMs seamlessly.

Describe alternatives you've considered.

Consider that all Open Source enthusiasts are using KernelSU as root solution for Custom ROMs now.

Additional context

No response

[tiann]

For non GKI kernel, no plan. For GKI kernel, #928