Added support to build in Linux RISCV64.

[goyox86]

Hi lua_ls team!

I recently manually built the server in my RISCV64 Ubuntu 24.10 Linux machine and so far it is working really well for me here.

It would be great that we would have riscv64 builds so things like mason.nvim work out of the box.

I just added some logic for the platform detection to work with riscv64 and changed the CH actions build script to install the cross compiler and toolchain for RISCV64, pretty much identical to the ARM64 steps.

Here is a small demo video:

Lua.Demo.webm

[sumneko]

I'm not very inclined to accept compilation support from other platforms within this project, because based on experience, they usually follow this pattern:

1. Accept a compilation PR from a platform.
2. It works fine for a long time.
3. One year later, when releasing a version, compilation failure is discovered.
4. I can't resolve the compilation issue, and I can't reach the original contributor, or they don't have the time and energy to resolve it.
5. To ensure a smooth release, the compilation for that platform is temporarily disabled, waiting for someone else to reactivate it.

I'm wondering if binary compilation and packaging should be separated into a standalone project?

[CppCXY]

please consider use the rust port for release, see: https://github.com/LuaLS/lua-language-server-rust