Allow S3-Compatible Cloud Object Storage in CloudETL Example

[metadaddy]

Description

This change allows the use of an S3-compatible cloud object store such as Backblaze B2 with the CloudETL example as an alternative to Amazon S3.

With this change, the user may configure an AWS profile with endpoint_url set to a value such as https://s3.us-west-004.backblazeb2.com in the config file. For example:

[profile b2-example]
endpoint_url = https://s3.us-west-004.backblazeb2.com
region = us-west-004

The setup_s3_storage.sh script reads this value (via aws configure get endpoint_url --profile $S3_PROFILE) into a new S3_ENDPOINT_URL environment variable which is used as store.url for the connectors. If the endpoint URL is not set in the profile, then the Amazon S3 global default, https://s3.amazonaws.com, is used.

There is also a fix to read-data.sh - the list-objects call was missing the --profile $S3_PROFILE, so it incorrectly used the default profile.

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[x] cloud-etl

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[ ] cloud-etl

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[metadaddy]

Hi @davetroiano - you replied to me on #1262 last month, pointing to the PR for the CLI 4 compatibles samples. Any interest in taking this on? It shows how you can send data to any S3-compatible cloud object store (Backblaze, Minio, IBM Cloud Object Storage, etc etc) by setting the endpoint and region in the AWS profile (which you've likely already done if you're using any of the AWS SDKs/CLI with one of those providers).