Add wasm support (#256)

* make wasm modules work when chunk deduplication is enabled
* make wasm modules work with chunks deduplication is disabled

Author: dario-piotrowicz

.changeset/flat-bobcats-glow.md

@@ -0,0 +1,49 @@
+---
+'@cloudflare/next-on-pages': patch
+---
+
+introduce wasm support
+
+introduce wasm support by tweaking how the wasm modules are imported, what `vercel build` does is adding dynamic
+requires at the top of the func files, like for example:
+
+```js
+// file: .vercel/output/functions/index.func/index.js
+const wasm_fbeb8adedbc833032bda6f13925ba235b8d09114 = require('/wasm/wasm_fbeb8adedbc833032bda6f13925ba235b8d09114.wasm');
+```
+
+then such identifier is used in the rest of the file (likely only inside chunks), as in:
+
+```js
+    // file: .vercel/output/functions/index.func/index.js
+    649:e=>{e.exports=wasm_fbeb8adedbc833032bda6f13925ba235b8d09114}
+```
+
+the above can't work with next-on-pages because:
+
+- dynamic requires are not supported
+- when we perform the chunks deduplication chunks containing such identifiers will not find their declaration causing
+  (e.g. a chunk file containing the `649` chunk code illustrated above won't know where `wasm_fbeb8adedbc833032bda6f13925ba235b8d09114`
+  comes from and would just provide a runtime error saying that it is not defined)
+- `/wasm/...` isn't a real directory, just some sort of convention used by vercel, the wasm files are located in the same
+  directory as the func file
+
+the adopted solution consists in:
+
+- copying the wasm files from their func relative locations into the `__next-on-pages-dist/wasm` directory
+- converting the func top level requires into standard relative esm imports, like for example:
+  ```js
+  // file: .vercel/output/functions/index.func/index.js
+  import wasm_fbeb8adedbc833032bda6f13925ba235b8d09114 from '../wasm/wasm_fbeb8adedbc833032bda6f13925ba235b8d09114.wasm';
+  ```
+  so that any part of the func file will be able to reference the variable (so that this works with chunks deduplication disabled)
+- adding similar import statements to any chunk files that reference these wasm identifiers, like for example:
+  ```js
+  // file: .vercel/output/static/_worker.js/__next-on-pages-dist__/chunks/649.js
+  import wasm_fbeb8adedbc833032bda6f13925ba235b8d09114 from '../wasm/wasm_fbeb8adedbc833032bda6f13925ba235b8d09114.wasm';
+  var a = b => {
+  	b.exports = wasm_fbeb8adedbc833032bda6f13925ba235b8d09114;
+  };
+  export { a as default };
+  ```
+  (so that this works with chunks deduplication enabled)