This pull request updates our usage of upload-artifact and download-artifact to v4. They introduced a breaking change which makes artifacts immutable, so we can't add more files to an already created artifact, a feature I relied on quite heavily. These are the changes:

• Actionlint complained about "number" in the inputs of dispatch_release.yml. I replaced that by string.
• I replaced v3 with v4 for all occurrences of upload-artifact and download-artifact. in a lot of actions
• Initially, we had an artifact named "logs" where all the logs were consolidated. In one of the later 3.x versions, I also added these logs to the artifacts which were created by every step. I now remove the functionality to add them to the consolidated "logs" archive. This will render the logfile.prefix setting obsolete.
• Initially, I created the "testplan" cached object to contain the initially generated testplan and then I used the begin-report action to add headers for the slack and summary report to the same archive. This has been streamlined by adding a new parameter "files" to the action and populating it with the files I initially uploaded. This eliminates one upload-artifact call as we add these files with begin-report now.
• The actions begin_report and append-report use unique artifact names starting with testplan- now. The action generate_report uses a new pattern matching feature to download all those artifacts matching testplan-* instead of the original "testplan" artifact. I am then creating a new "testplan" artifact from it afterwards and delete the testplan-* artifacts to clean up. The cleanup is still buggy, I have a ticket open with the author: Not all artifacts matching the glob are deleted GeekyEggo/delete-artifact#22)
• Breaking change: Whenever we create a code coverage file for sonarcloud, we now need different names for every artifact. So, we need to define a different prefix for every phpunit and codeception run. That means in every test plan using sonarcloud, we need to set a unique value for coverage.prefix. To pick up all those coverage reports, the sonarcloud action now uses the coverage_artifact parameter to define the pattern by which we choose the artifacts. In the universal workflow, I configured 'coverage-reports-**-${{ steps.sonarcloud_testplan_name.outputs.matrix_suffix }}', so all these coverage.prefix entries must start with "coverage-reports-".
• The output_artifact parameter of the son arcloud action was previously unused. I now use it to define the name for a consolidated artifact containing all reports. I also delete the artifacts which were consolidated.