[turbopack] Make it possible to synchronously access native bindings (#85787)
## Enable synchronous access to native bindings
## What?
This PR refactors the SWC bindings loading mechanism to support synchronous access to bindings after they've been loaded. It introduces new functions `installBindings()` and `getBindingsSync()` to properly manage the bindings lifecycle.
`installBindings` is called early by tools that rely on them.
There were of course a few complexities:
* webpack loaders need to defensively install bindings to support being run by webpack
* the hacky `loadNativeSync` method used by `transformSync` remains required due to the jest-transformer API (i didn't see a clear initialization location).
* the `experimental.useWasmBinary` configuration is broken by design
* if the config is `next.config.ts` when we load SWC to transpile it, but that requires the native bindings, so we might load native bindings even when you ask for wasm. I added a warning message for this case and the workaround is to use the node native transpilation support.
* this should probably be a command line flag if it is important
* we need to lazily load the `swc/index.ts` module since it transitively loads `react` which reads `NODE_ENV` and various next entrypoints might modify that.
## Why?
This makes it clearer that we are correctly applying the `useWasmBinary` option and can simplify some code paths that now don't need to be `async`. This will be important in a future PR where i move some parts of issue formatting into rust/wasm. Having those APIs be async will decrease their usability.