Add LLDB providers for BTreeMap and BTreeSet

[ede1998]

Fixes #111868.

I'm unsure what the supported LLDB versions for rust-lldb are. I tested with LLDB 18 and 19 and it works with those but I know that it does not work with LLDB 14 which was picked by my codelldb extension for some reason (even though it packages LLDB 19).

I also had to work around what seems like an LLDB bug to me. Otherwise, I'd have kept the code more similar to the GDB provider.
SBTarget.FindFirstType() does not find the types that I'm searching for (LeafNode<i32, i32>*):

target = node.GetTarget()
print("leaf type:", node.GetType())
internal_type = target.FindFirstType(node.GetType().GetName())
print("Actual type:", internal_type)

which prints

leaf type: struct alloc::collections::btree::node::LeafNode<int, int> *
Actual type: No value

All in all, my experience with LLDB debug provider was very fiddly/they seem to break easily but I think it would be better to have BTreeMap/BTreeSet providers than not have them.

Getting to run the debuginfo tests was a pain too because of #126092 and errors with import _lldb (#123621).
I ended up re-compling lldb from source against python 3.10 because the tests don't work if lldb is compiled against python 3.12.

Also, it seems like the tests are not run in CI? At least I had a test commit in the PR before to trigger a debuginfo test failure which I didn't see here in my PR.

[rustbot]

r? @Mark-Simulacrum

rustbot has assigned @Mark-Simulacrum.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[Mark-Simulacrum]

@rustbot author

[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[rustbot]

Some changes occurred in src/tools/compiletest

cc @jieyouxu

[ede1998]

@rustbot ready