Add another host for the CRS

[ludamad]

This will be where the CRS is downloaded from first. We will use the current bucket as a fallback.
We can use github potentially, but notably there are strict 100mb file limits or 4gb for github enterprise large file storage.

[johnathan79717]

Charlie's suggestion:

...for simplicity, cost, a reliability, for now we host on cloudflare r2 at foundation, and make that the primary pull point for everyone, with a fallback to the current labs s3 bucket.
and the buckets should have the same structure (serving the flat crs files, grumpkin and bn254 and g2 points), so we only need to change the domain in the event of failure.

[johnathan79717]

R2 bucket is set up. We had to register a new domain name on Cloudflare as it does not allow the free tier to use nameservers on Route 53.

File	URL
g1.dat	https://crs.aztec-cdn.foundation/g1.dat
g2.dat	https://crs.aztec-cdn.foundation/g2.dat
grumpkin_g1.dat	https://crs.aztec-cdn.foundation/grumpkin_g1.dat