ci: support merge queue

[knqyf263]

Description

This pull request introduces several enhancements to the Continuous Integration (CI) pipeline, explicitly focusing on the merge queue support. The changes are as follows:

• Merge queue support: This is a feature provided by GitHub that allows for a queue of pull requests to be merged automatically once the required checks pass. It triggers unit tests. More information about this feature can be found here.
• Integration test workflow: A new workflow file integration-test.yaml has been added. This workflow runs integration tests.
• Set unit tests as required: The unit tests have been set as required in the CI pipeline.
• Always run VM tests: The VM tests are now configured to always run in the CI pipeline.

Screenshot

The branch protection rule is as below:

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[knqyf263]

GitHub will merge all these changes into base_branch once the checks required by the branch protections of base_branch pass.

Seems like the required checks must be configured on the main branch. It doesn't fit our usage.

[afdesk]

LGTM