Builtin functions

[ghaith]

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

Some features of the standard functions work best as built-in functions provided by the compiler
Examples of such functions are ADR and REF, as well as functions that might take multiple parameters such as MUX, SEL, ADD..

Describe the solution you'd like

We should add support for functions that are always indexed, and generate IR for them on the fly
I suggest we start with ADR, REF and some of the math functions in table 29 of the norm. (ADD..)

Describe alternatives you've considered

Some of the functions are also possible to implement separately, I think we should find a balance here.
Functions that take variadic arguments cannot be implemented in rust, so we should at least provide a mechanism to convert these functions to equivalent callable functions.
Implementing the functions directly as builtin seems easier

[ghaith]

ADR and REF are in.

Find the balance for the rest as mentioned above