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

[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 att 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.

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Commit messages:
 - removed whitespace
 - reverted vmatree
 - more feedback fixes
 - Merge branch 'master' into rb-tree
 - encoded color in black height
 - removed split/merge/update_key
 - find_enclosing_range and edit key
 - test changes
 - iterator
 - min/max fix
 - ... and 5 more: https://git.openjdk.org/jdk/compare/a032de29...1b45feaf

Changes: https://git.openjdk.org/jdk/pull/22360/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22360&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8345314
  Stats: 1157 lines in 2 files changed: 1157 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