Vite embedded build of Element Call (#3077)

* Embedded package build of Element Call

Part of https://github.com/element-hq/element-call/issues/2994

This creates a new "embedded" build (vs "full" build) at the vite level. It will be used by a later PR that actually provides platform specific packages.

Embedded build:

- Uses relative URLs
- Uses relative config.json path and other resource loading
- Has a config.json built in
- Doesn't include the public folder (e.g. favicon)

Out of scope:

- this doesn't attempt to exclude SPA functionality, so technically the build could be used in SPA
- the above means that the crypto-wasm binary is included in the build

* CI artifact name based on type of build

* Update src/config/Config.ts

knip.ts

@@ -1,6 +1,9 @@
 import { KnipConfig } from "knip";
 
 export default {
+  vite: {
+    config: ["vite.config.js", "vite-embedded.config.js"],
+  },
   entry: ["src/main.tsx", "i18next-parser.config.ts"],
   ignoreBinaries: [
     // This is deprecated, so Knip doesn't actually recognize it as a globally