The idea is that we keep our DOAP file updated.
Then we always know which version of a XEP we implemented.
By running this script we can then find out if a new version of a XEP
came out.
And we can check whether we need to update our code to adhere to the
latest version or whether we can just version bump.
Move the `make doublecheck` functionality into a build system agnostic
script.
`scripts/quality-check.sh` can now be used to check for spelling via
codespell, formatting clang-format and run the unit tests.
`make doublecheck` and `meson compile doublecheck` will call this
script.
Sometimes we have issues with different versions of clang-format locally
vs our CI. In this case SKIP_FORMAT env variable can be set.
