s3mapprovider for Collector: load configuration from config files in Amazon S3

[rice-junhaoyu]

Description:
An implementation of ConfigMapProvider for Amazon S3 (s3mapprovider) allows OTEL Collector the ability to load configuration for itself by fetching and reading config files stored in Amazon S3.

This PR is the same PR as #13113, but requires me to open a new one due to my deactivated email address. It was already reviewed by @mx-psi and @Aneurysm9.

Link to tracking Issue:
#12939

Testing:
First, I mocked how a S3 client works while interacting with a S3 server.
Second, I designed and passed all the unit tests for edge cases such as empty fields, invalid config files, non-exist config files and so on.
Third, I did integration tests such as:

• Start an OTEL Collector with s3mapprovider.
• Start an OTEL sample application to send telemetry data to check if the OTEL Collector is running well.

Documentation:
Added a README.md

Sponsor:
@Aneurysm9

[mx-psi]

LGTM, I will merge once the CI passes. Thanks @rice-junhaoyu for taking the time to open this new PR and address the required changes :)

[jufemaiz]

Is this implementation operational in v0.76.0? I'm getting the following:

collector server run finished with error: unsupported scheme on URI "s3://BUCKET.s3.REGION.amazonaws.com/KEY"

[jufemaiz]

Apologies >< v0.72.0.

[Aneurysm9]

This is not available in the collector-contrib distribution as the collector builder does not yet have support for specifying which config providers to include. See open-telemetry/opentelemetry-collector#4759.

[jufemaiz]

@Aneurysm9 oh thank you for that clarification! It's not clear from the docs that that was the case!