web/satellite: web worker for wasm

WHAT:
web worker for compiling and instantiation of web assembly module

WHY:
Currently webassembly requires unsafe-eval, however we don't want to
add it to main site due to CSP. The workaround for this is to instantiate
wasm code inside a web worker.

Change-Id: I0c3c9cafa3a0c344761cf6dd86bf96248f1103ca

web/satellite/static/wasm/webWorker.js

@@ -0,0 +1,31 @@
+// Copyright (C) 2020 Storj Labs, Inc.
+// See LICENSE for copying information.
+
+importScripts('/static/static/wasm/wasm_exec.js')
+
+if (!WebAssembly.instantiate) {
+    self.postMessage(new Error('web assembly is not supported'));
+}
+
+const go = new Go();
+const instantiateStreaming = WebAssembly.instantiateStreaming || async function (resp, importObject) {
+    const response = await resp;
+    const source = await response.arrayBuffer();
+
+    return await WebAssembly.instantiate(source, importObject);
+};
+const response = fetch('/static/static/wasm/access.wasm');
+instantiateStreaming(response, go.importObject).then(result => go.run(result.instance)).catch(err => self.postMessage(new Error(err.message)));
+
+self.onmessage = function (event) {
+    const type = event.data.type;
+    switch (type) {
+        case 'GenerateAccess':
+            const result = self.generateAccessGrant();
+
+            self.postMessage(result);
+            break;
+        default:
+            self.postMessage(new Error('provided message event type is not supported'));
+    }
+};