Add missing tree implementations (AVL, AA, Red-Black, Splay, Treap, B-tree, Trie)

[evolve75]

New ordered/searchable tree types and their core operations are already implemented on next since R2.2.0.

[evolve75]

next already includes this work via the tree-type addition series, including AVL in 2062513 and Trie in bd09276 .
Keeping the issue open for tracking, but the missing-tree implementations are already present there.