Fix missing Kotlin stdlib versions in published POMs

[drganjoo]

Problem

Published Maven POMs were missing explicit version declarations for Kotlin stdlib dependencies (e.g., kotlin-stdlib-jdk8), causing dependency resolution issues for consumers of these artifacts.

Solution

This PR adds explicit version management for Kotlin stdlib dependencies in two places:

1. Resolution Strategy (smithy-rs.kotlin-conventions.gradle.kts):

   • Added a resolution strategy that forces all kotlin-stdlib-* dependencies to use the explicit version from the version catalog
   • Ensures consistent Kotlin stdlib versions across all modules at build time

2. POM Version Mapping (smithy-rs.publishing-conventions.gradle.kts):

   • Configured versionMapping for published POMs to include resolved versions from the runtime classpath
   • Ensures that transitive Kotlin dependencies have explicit versions in generated POMs
   • Applied to both java-api and java-runtime usages

Testing

• Build passes with explicit versions resolved for Kotlin stdlib dependencies
• Published POMs should now include proper version declarations for all Kotlin stdlib artifacts

[github-actions]

A new generated diff is ready to view.

• No codegen difference in the AWS SDK
• No codegen difference in the Client Test
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python
• No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

[aajtodd]

Odd that this is even necessary but seems ok.