Add metadata for flyway-core 10.15

[wilkinsona]

What does this PR do?

Adds metadata for 10.15 of org.flywaydb:flyway-core. Compared with the existing metadata for 10.10, it's only the addition of reflective access to all public methods of org.flywaydb.core.internal.publishing.PublishingConfigurationExtension.

Code sections where the PR accesses files, network, docker or some external service

None.

Checklist before merging

• I have considered including reachability metadata directly in the library or the framework (see our contributing document)
• I am the original author of all content provided in the pull request, and I did not copy the content from any other source (see the tests section from our contributing document)
• For all tests where I am not the sole author, I have added a comment that proves I may publish them under the specified license (see the tests section from our contributing document)
• I have properly formatted metadata files (see our formatting guide)
• I have added thorough tests (see the tests section from our contributing document)
• I have filled all places where my pull request accesses files, network, docker, or any other external service (see the section above)