fix: check common name for incompatible plugin

[JamesYFC]

Currently, the plugins check for the full names of the other plugin (pytest_playwright.pytest_playwright in async, and pytest_playwright_asyncio.pytest_playwright in sync) against the PytestPluginManager's name-to-plugin dict, in order to error if the other, incompatible, plugin has been loaded.

However, in my project (and it seems like this is pretty common), plugins will be registered under the "common" name:

And so this will fail to raise the error, and we will get this one instead which is much less helpful:

This PR does an additional check for the "common" name, and then checks that the plugin itself has the matching canonical name, which should now handle this case.

As far as I can see, I couldn't find a decent way to register a plugin under a different name as part of the pytest invocation, and so I haven't added the additional test case.

In the given example above though, this now gives us the expected error:

[JamesYFC]

@microsoft-github-policy-service agree [company="{your company}"]

@microsoft-github-policy-service agree [company="JamesYFC"]

[JamesYFC]

@microsoft-github-policy-service agree