Keep WireMockRule used as a server a WireMockServer; port() to getPort()

[timtebeek]

UseWiremockExtension turns every WireMockRule into a WireMockExtension, which breaks tests that call start(), stop(), isRunning() or port() on it, as WireMockRule extends WireMockServer.
The new WireMockRuleToWireMockServer recipe, run before it in JUnit4to5Migration, keeps a rule that is used with server lifecycle methods or passed on as a WireMockServer as a plain WireMockServer, started and stopped in @BeforeEach/@AfterEach (or static @BeforeAll/@AfterAll for a @ClassRule), reusing existing lifecycle methods where present.
It scans all sources, so a rule declared in a base class and stopped in a subclass is caught as well.
UseWiremockExtension now also rewrites port() and httpsPort() on the remaining rules to getPort() and getHttpsPort().
Tests cover both paths, standalone and through JUnit4to5Migration.