Inline assembly support

[keynmol]

This is a tracking issue for allowing to use inline assembly from Scala Native programs.

The mechanism by which this can be achieved is using the "Inline assembler expressions" in LLVM IR: https://llvm.org/docs/LangRef.html#inline-assembler-expressions

Prior art:

• Rust's inline asm! macro: https://doc.rust-lang.org/rust-by-example/unsafe/asm.html
• Clang's (see MacOS section) asm function: https://firexfly.com/clang-inline-assembly/

Considerations:

• Syntax - the main thing we'd need to support is some sort of string interpolation to allow referencing Scala definitions, translating them into addresses/constant values, and wiring in those translations in the LLVM IR
  Example:

val hello = 24
val str = c"yo"

inline_assembly(asm"""
mov X1, #5
mov W2, %${hello} ; transformed into the address of hello
mov W3, %${str}  ; transformed into the address of str in constant pool
""")

Reading material:

• https://llvm.org/docs/LangRef.html#inline-assembler-expressions
• https://llvm.org/devmtg/2021-11/slides/2021-handling-inline-assembly-in-clang-and-llvm.pdf

I'm not actually working on it, especially given I can't get any C examples to run on my Mac. This is merely an information dump