Fix determinism of compiled modules (#3229)

* Fix determinism of compiled modules

Currently wasmtime's compilation artifacts are not deterministic due to
the usage of `HashMap` during serialization which has randomized order
of its elements. This commit fixes that by switching to a sorted
`BTreeMap` for various maps. A test is also added to ensure determinism.

If in the future the performance of `BTreeMap` is not as good as
`HashMap` for some of these cases we can implement a fancier
`serialize_with`-style solution where we sort keys during serialization,
but only during serialization and otherwise use a `HashMap`.

* fix lightbeam

crates/lightbeam/wasmtime/src/lib.rs

@@ -9,7 +9,7 @@ use anyhow::Result;
 use cranelift_codegen::binemit;
 use cranelift_codegen::ir::{self, ExternalName};
 use std::any::Any;
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 use wasmtime_environ::{
     BuiltinFunctionIndex, CompileError, Compiler, FlagValue, FunctionBodyData, FunctionInfo,
     Module, ModuleTranslation, PrimaryMap, TrapInformation, Tunables, TypeTables, VMOffsets,
@@ -96,11 +96,11 @@ impl Compiler for Lightbeam {
         unimplemented!()
     }
 
-    fn flags(&self) -> HashMap<String, FlagValue> {
+    fn flags(&self) -> BTreeMap<String, FlagValue> {
         unimplemented!()
     }
 
-    fn isa_flags(&self) -> HashMap<String, FlagValue> {
+    fn isa_flags(&self) -> BTreeMap<String, FlagValue> {
         unimplemented!()
     }
 }