Add e2e test execution as task command

[maximiliantech]

Description

With the https://github.com/openmcp-project/service-provider-template and https://github.com/openmcp-project/openmcp-testing we have introduced the possibility to run tests for checking their Service providers' fundamentals end-to-end.

As part of the template, we have introduced a custom workflow that is executing the end-to-end tests in CI, see https://github.com/openmcp-project/service-provider-template/blob/main/.github/workflows/go.yaml

For that we have introduced custom Task commands to build the image and run the end-to-end tests, see
https://github.com/openmcp-project/service-provider-template/blob/38b3e591acda0824702bab1d5fe8b4aac33553ab/Taskfile.yaml#L16-L32

We should add that to the build repo to ensure that all Service Providers can import this functionality as part of their testing setup.

Tasks

• Add custom Task commands to shared build Task setup
• Add e2e workflow to share build CI workflow setup
• Prepare follow-up tasks in which repositories this needs to be integrated

Open questions

Is it safe to just copy/paste the custom Task commands or are there any dependencies we need to keep in mind?

Answer: Discuss this with @Diaphteiros