[lldb] [llvm] [LLDB] Add `ScalarLiteralNode` and literal parsing in DIL (PR #152308)

[Ilia Kuklin via llvm-commits]

kuilpd wrote:

`PickLiteralType` follows C++ logic, but this can later be put in a plugin if the logic doesn't apply everywhere. I'm not sure how to test this though, since the type is picked by width, so the resulting type name can be different on different machines.

I also split lexing number into 2 tokens to avoid parsing a single number token twice just to determine which number that is. I had to make `getAutoSenseRadix` in `StringRef` global to avoid copying that code into DIL, hopefully it's OK for it to be part of this patch and not a separate PR.

https://github.com/llvm/llvm-project/pull/152308