Implement open-test-reporting reader

See https://github.com/junit-team/junit5/issues/4113

> The Open Test Reporting format was introduced to replace the legacy XML format for test results in a way that supports all features of JUnit 5. It's designed to alleviate users from the mental load of having to translate from the logical structure of their test cases to an outdated technical format and vice versa. This task adds the missing pieces to make it truly useful and superior to the old format. This will reduce friction for our users by making it easier to understand test results and find the root cause of test failures and also make triaging bug reports easier for maintainers in the future because they will be able to request a test report which contains all relevant information.

It would be great if Allure could consume open-test-reporting report.

Start by reviewing the linked JUnit issue 4113 and the Open Test Reporting requirements described there. Then identify the Allure entry point for consuming test reports; done means Allure can consume an Open Test Reporting report and present its relevant test-result information.

Written by the indexing model from the issue text.