[llvm] Add new llvm.dbg.declare_value intrinsic. (PR #168132)

[J. Ryan Stinnett via llvm-commits]

jryans wrote:

Please also add this new record / intrinsic to the [source-level debugging docs](https://llvm.org/docs/SourceLevelDebugging.html#debug-records).

https://github.com/llvm/llvm-project/pull/168132