`char8_t`, `char16_t`, and `char32_t` should be highlighted as keywords

Checklist

- [x] This problem exists even with the setting `"C_Cpp.enhancedColorization": "Disabled"`

## The code with a problem is:
```cpp
char8_t x;
char x;
```

## It looks like:

![Image](https://github.com/user-attachments/assets/ba04e220-f050-4606-af03-8328d0dfa1d7)

## It should look like:
`char8_t` should have the same color as `char`.
