[llvm] [DebugInfo] Add DW_OP_LLVM_extract_bits (PR #93990)

[Stephen Tozer via llvm-commits]

SLTozer wrote:

> It would be more space-efficient to introduce two separate operations in in `u` and `s` variants, but I don't have any strong opinion either way.

I agree with this, we aren't squeezed for `DW_OP_LLVM_` operand space right now, but we care do care about the size of DIExpressions, so splitting into signed/unsigned variants would be better imo, unless there's a specific advantage to making the encoding an operand instead.

https://github.com/llvm/llvm-project/pull/93990