Remove some custom error types in Wasmtime (#5347)

* Remove some custom error types in Wasmtime

These types are mostly cumbersome to work with nowadays that `anyhow` is
used everywhere else. This commit removes `InstantiationError` and
`SetupError` in favor of using `anyhow::Error` throughout. This can
eventually culminate in creation of specific errors for embedders to
downcast to but for now this should be general enough.

* Fix Windows build

crates/runtime/src/lib.rs

@@ -55,7 +55,7 @@ pub use crate::externref::*;
 pub use crate::imports::Imports;
 pub use crate::instance::{
     allocate_single_memory_instance, InstanceAllocationRequest, InstanceAllocator, InstanceHandle,
-    InstantiationError, LinkError, OnDemandInstanceAllocator, StorePtr,
+    OnDemandInstanceAllocator, StorePtr,
 };
 #[cfg(feature = "pooling-allocator")]
 pub use crate::instance::{