Add bucket locks to dist-prod, dist-staging

[flakey5]

R2 supports bucket locking (https://developers.cloudflare.com/r2/buckets/bucket-locks/), this allows for writing new objects to a bucket but prevents overwriting. I'm not 100% sure this will work for our bucket structure, but I think we should look into using it since the majority of our assets are static and should never change

cc @nodejs/build since this requires someone with write access to R2

[richardlau]

I think this might make sense for dist-prod, but I think may not work for dist-staging (since rerunning release builds before being promoted should overwrite the staged assets).