Request for clang-format-{18 | 19} in asciidoctor-spec

Is it possible to have `clang-format-18` or `clang-format-19` installed in the `asciidoctor-spec` container?

Since `clang-format` behavior isn't stable across releases, I imagine that the default `clang-format` version in the container shouldn't change, since people could be relying on it. I.e., this is a request for `clang-format-18` in addition to the `clang-format` currently installed in the container.

In SYCL SC, we're currently getting `clang-format-19` from Debian Bookworm, but I'm not sure if this is the best way to do it:

```
add-apt-repository 'deb http://apt.llvm.org/bookworm/ llvm-toolchain-bookworm-19 main'
```

Locate the asciidoctor-spec container specification and inspect how the current clang-format package is installed. Compare the Debian Bookworm and apt.llvm.org options mentioned in the issue, then verify that the requested version is available alongside the existing default in a successful container build.

Written by the indexing model from the issue text.