[clang-format] [PR49298] Sort includes pass will sort inside raw strings

https://github.com/llvm/llvm-project/issues/48642

clang-format does not respect raw string literals when sorting includes

```
const char *RawStr = R"(
)";
```

Running clang-format over with SortIncludes enabled transforms this code to:

```
const char *RawStr = R"(
)";
```
The following code tries to minimize this impact during IncludeSorting, by treating R"( and )" as equivalent of // clang-format off/on

Reviewed By: HazardyKnusperkeks, curdeius

Differential Revision: https://reviews.llvm.org/D115168

Fixes #48642