Full proxy support in Bucket source

[darkowlzz]

#1500 introduced proxy support in Bucket source for generic provider.
The same proxy configuration should be usable when connecting to all the cloud providers as well.

• Update the Bucket reconciler to use any provided proxy configuration when connecting to all the cloud providers.
  • Google
  • Azure
  • AWS
• Update the docs to remove the mention of the proxy support being specific to the generic provider.

[matheuscscp]

I will update the docs to remove the mention of the proxy support being specific to the generic provider when merging the last of these 3 PRs:

• Add proxy support for GCS buckets #1565
• Add proxy support for Azure buckets #1567
• Add proxy support for AWS S3 buckets #1568 (this one is just updating the docs since the support was already implemented through the MinIO client, I plan to merge this one in the end, rebasing and removing the doc mention after merging the other 2 PRs)