MISC: Support compression of save data (#1162)

* Use Compression Streams API instead of jszip or other libraries.
* Remove usage of base64 in the new binary format.
* Do not convert binary data to string and back. The type of save data is SaveData, it's either string (old base64 format) or Uint8Array (new binary format).
* Proper support for interacting with electron-related code. Electron-related code assumes that save data is in the base64 format.
* Proper support for other tools (DevMenu, pretty-save.js). Full support for DevMenu will be added in a follow-up PR. Check the comments in src\DevMenu\ui\SaveFileDev.tsx for details.

electron/saveDataBinaryFormat.js

@@ -0,0 +1,13 @@
+// The 2 magic bytes of the gzip header plus the mandatory compression type of DEFLATE
+const magicBytes = [0x1f, 0x8b, 0x08];
+
+function isBinaryFormat(rawData) {
+  for (let i = 0; i < magicBytes.length; ++i) {
+    if (magicBytes[i] !== rawData[i]) {
+      return false;
+    }
+  }
+  return true;
+}
+
+module.exports = { isBinaryFormat };