Add support for KOSM

[mntzrr]

Task: https://app.clickup.com/t/8694bpdkb

[MichaelBengtsson]

@mntzrr I'm sorry, i missed the needed changes to .distignore with this PR. Should have mentioned that earlier as well.

You need to add the new composer-depencencies files, any potential tmp or vendor folders, and the scoper.custom.php file to these as well. For the composer files, i suggest not using a wildcard with composer as the base, since that might exclude files in the dependencies folder as well, which handles the autoloading for them. So exclude them more directly than that.

We have this in other plugins that use a similar build process. So you can reference those.

We will also need to add changes to the deployment action before we release this, since we need to add the composer step to build the actual release. But that should be fairly simple to do. We can discuss this internally today if you have time.