RFR: 8366457: Add ResourceArea and Arena allocators for the RBTree

[Afshin Zafari]

On Wed, 7 Jan 2026 09:37:50 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

> This PR adds Arena and ResourceArea allocators to the RBTree. The test checks that we can make RBTrees from these allocators and that a basic upsert works.

Thank you for this new feature.
Copyright year of the files are not updated.

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PR Review: https://git.openjdk.org/jdk/pull/29082#pullrequestreview-3772369891