Add support for LLVM target

[tropicahq]

It would be a nice choice to have llvm target for gleam, just to explore another target for the language other that javascript and erlang vm. I'll like to explore adding it my self just to see how it goes, but I need pointers for where to start from.

[GearsDatapacks]

Hi, thank you for your interest in contributing. Unfortunately a new target would be a massive amount of work for us to build and maintain, something which we don't really have the resources to do at the moment.
Additionally, before adding a new target, we would need to do research in order to determine how it would fit with the existing Gleam ecosystem, how it would complicate it, as well as what benefits there are to a new target.

You're welcome to fork the compiler and have a go at implementing an LLVM backend yourself, many have done so before (with various different backends), but it is unlikely that we would accept a PR for that, unless provided with sufficient evidence to support its addition, as well as funding to continue developing and maintaining it.