Add automated test for "Export Import a document with history"

The manual test is here: Export Import a document with history

Existing automated coverage

• XARImportIT#testImportWithHistoryWhenNoPage: Import UI: upload a prebuilt XAR with history, select it, choose "Replace the page history with the history from the package", import, and assert versions and comments in the history tab (main wiki).
• XARImportIT#testImportWithHistoryWhenPage: Same import with history when the page already exists.
• ExportActionTest#exportPartialXAR: Unit test of the XAR export action with history=true (mocked).

Missing automated coverage

• Create nested page 1/2 and save several versions (add text, remove text, add a table, add a link)
• Export it with bin/export/1/2/WebHome?format=xar&name=1.2.WebHome&pages=xwiki%3A1.2.WebHome&history=true
• Create a subwiki and import the exported XAR from its Administer Wiki > Content > Import with "Replace the page history with the history from the package"
• Assert the imported page history in the subwiki has the same versions and comments as the original

Suggested location: xwiki-platform-core/xwiki-platform-administration/xwiki-platform-administration-test/xwiki-platform-administration-test-docker/src/test/it/org/xwiki/administration/test/ui/XARImportIT.java

Found by comparing the XWiki 18.4.4 manual test runs against the automated tests on master (a0055f10a1a).