Promote incubating org.gradle.api.provider.ValueSource and family

[bamboo]

Summary

• org.gradle.api.provider.ValueSource
• org.gradle.api.provider.ValueSourceParameters
• org.gradle.api.provider.ValueSourceParameters.None
• org.gradle.api.provider.ValueSourceSpec

Checklist

• Validate whether we should de-incubate the API in the 7.0 release.
  • If the removal is not possible, create a follow-up issue and link it in the overview spreadsheet
• Update release notes (add API to promoted features)
• Check User Manual (it might mention that the API is still incubating)
  • Think about updating snippets and samples to use this API
• Deprecate existing API that is replaced by the new one
  • If it's not immediately possible, create a follow-up issue with a milestone (e.g. 7.1 RC1 or 8.0 RC1)
• Check Incubation Report on TeamCity (example)
• Mark the story as done in the overview spreadsheet.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. Given the limited bandwidth of the team, it will be automatically closed if no further activity occurs. If you're interested in how we try to keep the backlog in a healthy state, please read our blog post on how we refine our backlog. If you feel this is something you could contribute, please have a look at our Contributor Guide. Thank you for your contribution.

[stale]

This issue has been automatically closed due to inactivity. If you can reproduce this on a recent version of Gradle or if you have a good use case for this feature, please feel free to to let know so we can reopen the issue. Please try to provide steps to reproduce, a quick explanation of your use case or a high-quality pull request.