Add support for setting proxy on aws client

Describe the bug
Trying to use spring cloud config server with s3 as backend and using proxy credentials to connect to AWS s3. And got this exception when I have .credentials file in /.aws/ directory. I have embedded config server in one application.

bootstrap.yml

spring:
  profiles:
      active: awss3
  cloud:
    config:
      server:
        awss3:
          region: us-east-1
          bucket: sample-bucket
        default-label: sample-config
        default-profile: test
        default-application-name: awss3-demo
        bootstrap: true

application.yml

server:
  port: 8080

Sample
Got below exception in AwsS3EnvironmentRepository.java class when finding the config file in s3 with the default credentials
eYaml = {SdkClientException@5620)com.amazonaws.SdkClientException: Unable to execute HTTP request: Connection reset

Any Help will be great. Thank you.

Start by reading AwsS3EnvironmentRepository.java and how its AWS client is constructed, using the supplied bootstrap.yml and application.yml as the reproduction context. Investigate how proxy credentials could be supplied for the S3 connection; done means the config server can retrieve configuration from S3 through the proxy without the connection-reset exception.