Move address maps to a section of the compiled image (#3240)

This commit moves the `address_map` field of `FunctionInfo` into a
custom-encoded section of the executable. The goal of this commit is, as
previous commits, to push less data through `bincode`. The `address_map`
field is actually extremely large and has huge benefits of not being
decoded when we load a module. This data is only used for traps and such
as well, so it's not overly important that it's massaged in to precise
data the runtime can extremely speedily use.

The `FunctionInfo` type does retain a tiny bit of information about the
function itself (it's start source location), but other than that the
`FunctionAddressMap` structure is moved from `wasmtime-environ` to
`wasmtime-cranelift` since it's now no longer needed outside of that
context.

crates/environ/src/compilation.rs

@@ -2,8 +2,8 @@
 //! module.
 
 use crate::{
-    DefinedFuncIndex, FunctionAddressMap, FunctionBodyData, ModuleTranslation, PrimaryMap,
-    StackMap, Tunables, TypeTables, WasmError, WasmFuncType,
+    DefinedFuncIndex, FilePos, FunctionBodyData, ModuleTranslation, PrimaryMap, StackMap, Tunables,
+    TypeTables, WasmError, WasmFuncType,
 };
 use anyhow::Result;
 use object::write::Object;
@@ -21,7 +21,7 @@ use thiserror::Error;
 #[allow(missing_docs)]
 pub struct FunctionInfo {
     pub traps: Vec<TrapInformation>,
-    pub address_map: FunctionAddressMap,
+    pub start_srcloc: FilePos,
     pub stack_maps: Vec<StackMapInformation>,
 }