Checksum validation for better security

[nileshtrivedi]

Loading third-party scripts via a loader gives us an opportunity to do checksum validation and avoid exploits made by bad third-party code. Idea is from this Twitter thread:

The checksum could be a self-descriptive multihash for future-proofing.

[tosmolka]

This could be achieved by adding support for Subresource Integrity to script.js