Space name cleanup: not for the data space, but only for the code space

Split off from XWIKI-11025:
as pointed out by mflorea, the AppWithMinutes "cleaned up" the data space for the new application (even though the UI says it does not).

Instead it should clean up the code space,as the name of the code space might be used in css classes / html element ids etc.

Example: User types in 'my new app.'
Should create:

• data space 'my new app.'
• code space: 'mynewappCode'

Currently creates:

• data space: 'mynewapp'
• code space: 'my new app.Code'