Write pprof downloads to object storage

[metalmatze]

Users can request a .pb.gz pprof file from Parca (report type REPORT_TYPE_PPROF).
These downloads can grow quite large.

We propose not downloading these pprofs via the browser but instead uploading the file to a remote location, similar to the share profile functionality. Parca would expect a pre-signed URL for S3-compatible storage and then upload the file to that location.

Bonus: We can ensure that it also works with a location to a filesystem-based S3 bucket, such that the file gets written to disk.