Add automated test for "Grant Create Wiki Right For An User"

The manual test is here: Grant Create Wiki Right For An User

Existing automated coverage

None found.
Searched the wiki, administration and security test modules for createwiki, CREATE_WIKI, Creation Right and WikiCreationRights; every UI wiki creation (SubWikiIT, WikiTemplateIT) runs as superadmin. Related only: WikiManagerRestIT#testCreateWiki checks that a user without the right is refused over REST, and WikiManagerScriptServiceTest checks the right with mocks.

Missing automated coverage

• As superadmin open Administer Wiki > Wikis > Creation Right, select the Users radio button, grant Create Wiki to a new non-admin user and save
• Log in as that user, go to the Wiki Index and assert the Create Wiki action is offered
• Run the wizard (WikiIndexPage#createWiki > CreateWikiPage > goUserStep().create() > WikiCreationPage) and assert the wiki is created and its home page is displayed
• Assert that a user without the right is not offered the Create Wiki action
• Add a page object for the Creation Right administration section (EditRightsPane may be reusable)

Suggested location: xwiki-platform-core/xwiki-platform-wiki/xwiki-platform-wiki-test/xwiki-platform-wiki-test-docker (new WikiCreationRightIT)

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