XWIKI-6700 : Copying a page over an existing one does not warn user.

Add integration test for the overwrite prompt.
XWIKI-9549: Merge log does not end up in the XAR extension install log
* Update functional test.
[misc] Remove unrelated javadoc.
[release] Updated translations.
Merge remote-tracking branch 'upstream/master' into feature-new-wiki-api
XWIKI-9516: Create a new Wiki API that replaces xwiki-platform-wiki-manager and xwiki-platform-workspace.

* Integrate the new wiki API & UI in enterprise.