Replace Gradle Nexus plugin with hand-written API integration

[ianbotsf]

Describe the feature

Our Gradle Nexus plugin functions adequately much of the time but has two problems:

• It occasionally times out too quickly while waiting for repository states to transition (despite seemingly-generous timeout configuration)
• It does not support atomically publishing multiple groups simultaneously because of gradle-nexus/publish-plugin#109 (e.g., aws.sdk.kotlin for runtime and software.amazon.smithy.kotlin for codegen have to be published separately)

To work around these issues, we should replace our usage of the plugin with handwritten code that directly invokes Sonatype's REST API.

Is your Feature Request related to a problem?

Yes, see above.

Proposed Solution

See above.

Describe alternative solutions or features you've considered

This is an alternative solution to the existing solution of Nexus publishing via a plugin.

Acknowledge

• [X] I may be able to implement this feature request

AWS Kotlin SDK version used

0.17.6-beta

Platform (JVM/JS/Native)

JVM 8+

Operating System and version

Amazon Linux 2