Clarification needed for language restrictions related to RTTI

The spec currently says the following in [5.4. Language restrictions for device functions](https://registry.khronos.org/SYCL/specs/sycl-2020/html/sycl-2020.html#sec:language.restrictions.kernels):

https://github.com/KhronosGroup/SYCL-Docs/blob/9b616cef64dbdd658cb5fb6bcaf9e0bac22cad17/adoc/chapters/device_compiler.adoc?plain=1#L168

It is not entirely clear to me what exactly is meant by "RTTI is disabled". From what I understand, RTTI is a part of C++ language and can't be disabled from language point of view. At least I don't see anything which would suggest optionality of that functionality in [support.rtti](https://eel.is/c++draft/support.rtti), [expr.typeid](https://eel.is/c++draft/expr.typeid) or [expr.dynamic.cast](https://eel.is/c++draft/expr.dynamic.cast). Perhaps I'm missing something here?

It would be great to be more precise here with which exact C++ RTTI-related constructs are illegal in device code, such as: an `typeid` be used there? Can `dynamic_cast` be used in there?

Start with the language-restrictions section in adoc/chapters/device_compiler.adoc at the cited line, then compare its RTTI wording with the linked C++ clauses for typeid and dynamic_cast. Clarify which RTTI-related constructs are permitted or forbidden in device code, and update the specification text so the restrictions are explicit.

Written by the indexing model from the issue text.