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

.github/workflows/deploy-to-netlify.yaml

@@ -50,7 +50,7 @@ jobs:
         with:
           github-token: ${{ secrets.ELEMENT_BOT_TOKEN }}
           run-id: ${{ inputs.artifact_run_id }}
-          name: build-output
+          name: build-output-full
           path: webapp
 
       - name: Add redirects file