[clang] [lldb] [HLSL] Implement intangible AST type (PR #97362)

[Helena Kotas via cfe-commits]

hekota wrote:

@ChuanqiXu9 - any idea why is your new test `Modules/no-external-type-id.cppm` failing on my PR?
It is expecting `// CHECK: <DECL_FUNCTION {{.*}} op8=4048` in the llvm-bcanalyzer output and it gets `op8=4056`.

https://github.com/llvm/llvm-project/pull/97362