Fix some errors. Remove @ts-ignores
Convert some files to TS
Remove some eslint-disables

Found via `codespell -q 3 -S ./lang -L miliseconds`

In cross origin issolated mode we need to explicitly add crossOrigin
attribute for all resources that are loaded with CORS headers.

Fixes: https://github.com/jitsi/jitsi-meet/issues/8510

This basically reverts
a3fb996ff0
while retaining the same properties that prompted it's original intent, namely
avoiding sending the Referrer header.

Use fetch(), which gives us better control over headers.