Refactoring work to support multi-tenancy and multiple storage, database backends (#598)

* Backend infrastructure
* New backend configuration work
* Factor out KV prefixing
* Don't put assets in the manifest cache
* Removed fancy authentication stuff
* Documentation updates

server/crypto.ts

@@ -0,0 +1,13 @@
+export async function hashSHA256(message: string): Promise<string> {
+  // Transform the string into an ArrayBuffer
+  const encoder = new TextEncoder();
+  const data = encoder.encode(message);
+
+  // Generate the hash
+  const hashBuffer = await window.crypto.subtle.digest("SHA-256", data);
+
+  // Transform the hash into a hex string
+  return Array.from(new Uint8Array(hashBuffer)).map((b) =>
+    b.toString(16).padStart(2, "0")
+  ).join("");
+}