no LLDB pretty printer for BTreeMap

[jendrikw]

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rustc --version --verbose:

rustc 1.77.1 (7cf61ebde 2024-03-27)
binary: rustc
commit-hash: 7cf61ebde7b22796c69757901dd346d0fe70bd97
commit-date: 2024-03-27
host: x86_64-unknown-linux-gnu
release: 1.77.1
LLVM version: 17.0.6

https://github.com/rust-lang/rust/blob/master/src/etc/lldb_providers.py and https://github.com/rust-lang/rust/blob/master/src/etc/lldb_lookup.py only have pretty printers for HashMap, not BTreeMap.

The screenshot is from Rustrover.
(Unrelated, but the Rc as part of the value type parameter is missing it's type parameters)