Improving security of window.ipfs (low hanging fruits)

[lidel]

• fix: restrict window.ipfs to Secure Contexts (closes Restricting window.ipfs to Secure Context #476, closes Chrome Error: Please use a browser with webcrypto support #475)
• fix: introduce global whitelist for window.ipfs (closes Disable sensitive APIs (eg. window.ipfs.config). Provide a capabilities API. #478, mitigates Add scoping for window.ipfs.name.publish and window.ipfs.key #452)
  • Note: This is a temporary measure we need to ship ASAP to mitigate risk until we move API whitelist to ipfs-postmsg-proxy and stop exposing methods at all (as noted in Support explicit whitelist of exposed APIs ipfs-inactive/ipfs-postmsg-proxy#29)

@olizilla please take a look, I want to merge this today 🐎