This commit refactors where trampolines and signature information is stored within a `Store`, namely moving them from `wasmtime_runtime::Instance` instead to `Store` itself. The goal here is to remove an allocation inside of an `Instance` and make them a bit cheaper to create. Additionally this should open up future possibilities like not creating duplicate trampolines for signatures already in the `Store` when using `Func::new`.
This is the wasmtime-jit crate, which contains JIT-based execution
for wasm, using the wasm ABI defined by wasmtime-environ and the
runtime support provided by wasmtime-runtime.
Most users will want to use the main wasmtime crate instead of using this
crate directly.