Add support for alias registers

[amykyta3]

Title is pretty self-explanatory.
Add code generation support for registers that are described as aliases.

[rakesh2215]

I believe alias is used extensively to implement force/disable interrupts.
@amykyta3
Given the nature of the alias feature [write to int_force_reg and it affects int_status_reg], is this too tricky to add this feature?
If possible, please drop hints on where the code change would be.