RFR: 8345314: Add a red–black tree as a utility data structure [v17]

[Casper Norrbin]

> Hi everyone,
> 
> This effort began as an exploration of replacing the current NMT treap with a red-black tree. Along the way, I discovered that others were also interested in having a general-purpose tree structure available within HotSpot.
> 
> The red-black tree is designed to serve as a drop-in replacement for the existing NMT treap, keeping a nearly identical interface. However, I’ve also added a few additional requested features, such as an iterator.
> 
> Testing builds off the treap tests, adding a few extra that inserts/removes and checks that the tree is correct. Testing uses the function `verify_self`, which iterates over the tree and checks that all red-black tree properties hold. Additionally, the tree has been tested in vmatree instead of the treap without any errors.
> 
> For those who may want to revisit the fundamentals of red-black trees, [Wikipedia](https://en.wikipedia.org/wiki/Red%E2%80%93black_tree) offers a great summary with tables covering the various balancing cases. Alternatively, your favorite data structure book could provide even more insight.

Casper Norrbin has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 36 commits:

 - merge fixes
 - Merge branch 'master' into rb-tree
 - readd find_enclosing_range
 - Merge branch 'master' into rb-tree
 - treap swap fix
 - const functions
 - thomas feedback
 - axel feedback
 - clarified comment
 - Improved comments
 - ... and 26 more: https://git.openjdk.org/jdk/compare/ad01dfb6...b7219a93

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Changes: https://git.openjdk.org/jdk/pull/22360/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22360&range=16
  Stats: 1435 lines in 3 files changed: 1435 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22360.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22360/head:pull/22360

PR: https://git.openjdk.org/jdk/pull/22360