CreateWiki: Next step button remains disabled if one fills the wiki identifier before the pretty name

So, this part of the code assumes that we need a pretty name, which makes sense.
https://github.com/xwiki/xwiki-platform/blob/a00e71e026b280cf5e738e3b60420e6d80f7522f/xwiki-platform-core/xwiki-platform-wiki/xwiki-platform-wiki-ui/xwiki-platform-wiki-ui-mainwiki/src/main/resources/WikiManager/CreateWiki.xml#L915-L917
However, when we change the prettyName, the verification is only done if the wikiname (non prettyName) was not set.
https://github.com/xwiki/xwiki-platform/blob/a00e71e026b280cf5e738e3b60420e6d80f7522f/xwiki-platform-core/xwiki-platform-wiki/xwiki-platform-wiki-ui/xwiki-platform-wiki-ui-mainwiki/src/main/resources/WikiManager/CreateWiki.xml#L864-L867

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In this use case, those two facts create the usability issue.
In order to solve it, we need to change one of the two behaviours slightly:
Either A. we don't need a pretty name (I wouldn't advise to make this change)
OR B. we validate the validity of the wikiname EVERYTIME when the pretty name is changed.

I'm for option B. each validation is a request to the server so we need to make sure we don't overdo it (e.g. one request per letter typed in the prettyName... ).