Rework unit tests to not depend on external website

[Don-vip]

We still have some unit tests making real network connections, failing when the website is slow or unreachable:

1. ✔ org.openstreetmap.josm.gui.oauth.OsmOAuthAuthorizationClientTest.testCookieHandlingMock
2. org.openstreetmap.josm.gui.oauth.OsmOAuthAuthorizationClientTest.testCookieHandlingCookieManager
3. ✔ org.openstreetmap.josm.gui.preferences.server.ApiUrlTestTaskTest.testNominalUrl
4. ✔ org.openstreetmap.josm.gui.preferences.server.ApiUrlTestTaskTest.testAlertInvalidServerResult
5. ✔ org.openstreetmap.josm.io.OsmServerHistoryReaderTest.testWay
6. ✔ org.openstreetmap.josm.io.OsmServerHistoryReaderTest.testNode
7. org.openstreetmap.josm.tools.HttpClientTest.testOpenUrlBzip
8. org.openstreetmap.josm.tools.HttpClientTest.testOpenUrlGzip
9. org.openstreetmap.josm.tools.HttpClientTest.testTicket9660

[ris]

There also those that unintentionally make network requests, e.g. fetching the "start page" from the wiki.

[Don-vip]

In 14191/josm:

see #16637 - javadoc

[simon04]

Related: #15102

[Don-vip]

In 17075/josm:

see #15102 - see #16637 - get rid of real HTTP calls to ​http://httpstat.us in unit tests, mock them

[Don-vip]

In 17154/josm:

see #15102 - see #16637 - get rid of real HTTP calls to ​https://httpbin(go).org in unit tests, mock them

[simon04]

In 17189/josm:

see #15102 - see #16637 - get rid of real HTTP calls to https://josm.openstreetmap.de/josmticket in unit tests, mock them

[simon04]

In 17192/josm:

see #15102 - see #16637 - get rid of real HTTP calls to ​https://api.openstreetmap.org in ApiUrlTestTaskTest, mock them

[simon04]

In 17194/josm:

see #15102 - see #16637 - get rid of real HTTP calls to ​https://api.openstreetmap.org in OsmServerHistoryReaderTest, mock them

[simon04]

In 17195/josm:

see #15102 - see #16637 - Use WireMockServer.url()

[simon04]

In 17196/josm:

see #15102 - see #16637 - get rid of real HTTP calls to ​https://www.openstreetmap.org/login in OsmOAuthAuthorizationClientTest, mock them