feat: range requests for certified assets

[lastmjs]

Original issue, not sure if I should move it to this repo: https://github.com/dfinity/certified-assets/issues/10

This was originally pull-requested here: https://github.com/dfinity/certified-assets/pull/21

I'm still cleaning up a bit and doing some testing, but I would love to get feedback. Besides minor cleanup and some possibly optional features missing as described here https://github.com/dfinity/certified-assets/issues/10, I am done with the implementation of range requests.

[lastmjs]

I'm not sure how to move forward after this conversation: https://forum.dfinity.org/t/boundary-node-http-response-headers/10747/6

If the ETA on boundary nodes serving partial responses is far into the future, then I'm wondering if we can get this PR merged in the mean time, or if I should just maintain a fork for those interested in the functionality until the more scalable and robust boundary node version is deployed.