Add ServiceURL option for KMS client

[bdurrani]

AmazonKeyManagementServiceConfig doesn't use the service url when it's setting on AmazonS3CryptoConfigurationV2

Description

Motivation and Context

I'm using LocalStack when I set ServiceURL on AmazonS3CryptoConfigurationV2 I'm seeing the Kms calling aws endpoint

See #29 for reference

Testing

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed

License

• I confirm that this pull request can be released under the Apache 2 license

[bdurrani]

@normj Hi there
Is this change ok for the KMS client ServiceURL option?
As discussed here: #29

Thanks

[ashovlin]

Looks good to me, I'll line up a second reviewer from the internal team. We'll also handle the version bump once approved.

[ashovlin]

I've merged this to dev, which is our staging branch for the next release. We'll reply again once the new release is out.

[ashovlin]

This PR was released yesterday in 2.1.0, thanks again for your contribution!