feat: router-based wasm bundle splitting (#3683)

* feat: wasm-split base implementation

* kinda sorta works with the cli

* okay great it actually works

* fix: cache busting for chunks

* cleaned up version

* it works with the router

* wip: migrate to a faster linear solution using id remapping

* add a good harness

* it works completely on the docsite

* the super tight build works too

* make parallelizable

* works on the docsite but not the harness

* light cleanups, fix for both harness and docsite

* make codegen smaller by extract some shared functions to prevent monos

* chunking works, but tbd on tuning heuristics

* extract used module

* wip: cleaning up module

* wip: much better understanding of how imports work

* fix the call graph

* working again...

* wip: thinking about ifuncs

* ifunc approach works

* yes the ifunc approach works!!

* it all works completely even with chunks

* small cleanups

* comments

* actually locate all of the symbols

* clean up final implementation

* clean up tomls, revert some mono changs

* clean up, add some more comments / docs in places

* hoist more packages

* clean up impl a bit more

* clean cli

* move harness to playwright

* update playwright

* extract codgen

* add lazy to components

* Add docs to split loader

* clippy

* typos

* clippy, don't generate splits if not on wasm

* whoops, const

* Typos and docs

* enable optimizations in ci

* add optimizations to ci

* add wasm-split router feature

* parallel playwright?

* fix no case check

* disable pre-compress... think that might be the issue

* better logging, no default pre-compress, caching of shared symbols
* Fix: compressing assets

* fix non-interactive logging for serve

* cache playwright even on failure, use the cli with optimizations

* fix prebuild

* fix playwright webserver

packages/cli/src/build/request.rs

@@ -340,6 +340,14 @@ impl BuildRequest {
 
         cargo_args.push(self.krate.executable_name().to_string());
 
+        // the bundle splitter needs relocation data
+        // we'll trim these out if we don't need them during the bundling process
+        // todo(jon): for wasm binary patching we might want to leave these on all the time.
+        if self.build.platform() == Platform::Web && self.build.experimental_wasm_split {
+            cargo_args.push("--".to_string());
+            cargo_args.push("-Clink-args=--emit-relocs".to_string());
+        }
+
         tracing::debug!(dx_src = ?TraceSrc::Build, "cargo args: {:?}", cargo_args);
 
         cargo_args
@@ -658,7 +666,7 @@ impl BuildRequest {
 
     /// Get the path to the wasm bindgen temporary output folder
     pub fn wasm_bindgen_out_dir(&self) -> PathBuf {
-        self.root_dir().join("wasm-bindgen")
+        self.root_dir().join("wasm")
     }
 
     /// Get the path to the wasm bindgen javascript output file