iwyu.imp

See the [OSC 8 page](https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda).
FTXUI support proposed by @aaleino in [#662](https://github.com/ArthurSonzogni/FTXUI/issues/662).

API:
```cpp
auto link = text("Click here") | hyperlink("https://github.com/FTXUI")
```

Fixed:https://github.com/ArthurSonzogni/FTXUI/issues/662