Add clang-format to Dev Container

[calebchalmers]

We are running into issues with our CI using a different version of clang-format than people's local machines which is causing the super-linter jobs to fail.

Generally, the local clang-format binaries come from either the users machine, or the VS Code cpptools extension, which includes a binary in the package.

To avoid versioning issues, we can install a specific clang-format version inside the Dev Container and then force that in .vscode/settings.json. Note, we will also need to downgrade super-linter to a compatible version.