[lldb] Implement bytecode based SyntheticChildren (#179832)
Initial implementation of a [bytecode][1] synthetic provider. This is a follow up to
https://github.com/llvm/llvm-project/pull/114333 which implemented the bytecode
interpreter, support for summary formatters, and more.
rdar://169727764
[1]: https://lldb.llvm.org/resources/formatterbytecode.html