feat: replace credentials and providers with v2

[jvdadda]

Description of changes:

Replace all aws-sdk-java-v1 providers with sdk-v2:

• com.amazonaws.auth.AWSCredentialsProvider > software.amazon.awssdk.auth.credentials.AwsCredentialsProvider
• com.amazonaws.auth.DefaultAWSCredentialsProviderChain > software.amazon.awssdk.auth.credentials.DefaultCredentialsProvider
• com.amazonaws.auth.AWSCredentials > software.amazon.awssdk.auth.credentials.AwsCredentials
• Removal of EnhancedProfileCredentialsProvider to directly use it
• com.amazonaws.services.securitytoken.* replaced by call of StsClient
• all Credential providers replaced by v2 equivalent (cf https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/migration-client-credentials.html)

Some changes have been made in unit tests:

• aws.secretKey > aws.secretAccessKey
• mock resolveIdentity instead of resolveCredentials

Remaining to migrate:

• import com.amazonaws.AmazonWebServiceRequest;
• import com.amazonaws.DefaultRequest;
• import com.amazonaws.auth.AWS4Signer;
• import com.amazonaws.auth.internal.SignerConstants;
• import com.amazonaws.http.HttpMethodName;
• import com.amazonaws.partitions.PartitionsLoader;
• import com.amazonaws.regions.Region;
• import com.amazonaws.regions.RegionMetadata;
• import com.amazonaws.regions.Regions;
• import com.amazonaws.util.ClassLoaderHelper;
• import com.amazonaws.util.VersionInfoUtils;

[!WARNING] Waiting merge of https://github.com/aws/aws-msk-iam-auth/pull/156

[rajarshp]

@jvdadda @sidyag - could you please let me know if these fixes are ready ? we are waiting for this fixes to be available to use.