Support for no_std in cranelift_codegen and cranelift_assembler_x86

[the-ssd]

Closes #1158, allows for cranelift to be used in a no_std environment, like a kernel.

There is already #9007, which stalled.

And I am at a point I think it makes sense to ask someone what do you want to be done about FxHashMap and OnceLock. There are alternative crates that implement it, like this one (also has a comparison chart).

What is left to do:

• isle codegen generates code that depends on no_std, solved in the previous PR (https://github.com/bytecodealliance/wasmtime/pull/9007/files#diff-0496ab91e0634653bd3d4295c7aa90e3f06b0c5f462332db0997a22f294cbf94)
• separate PRs for: cranelift_assembler_x86, moving large parts to core and alloc, and isle
• floating point issues

For codegen I also added a prelude file, with all imports, because it was easier this way for now. I put preludes at the bottom, because at the top, some file would break because of ///! doc comments. Should I redo it, and move them to the top, or avoid prelude fully?

Edit: prelude can be added by replacing first use of use with use crate::prelude::*;\n use instead of putting it at the bottom