Restore Sites Management module

[mhsdesign]

With #4718 the index action works barely again

• Problem is, it only works, if there is already a neos site on the system

• Also if no cr is setup we should show the cli guide how to setup a cr or redirect to FEATURE: Content Repository Maintenance Module #4773

• Another problem is that the Import a site step doesnt work as there is no importSiteAction as this logic is currently commented out.

• The Create a blank site actually works if you select the correct nodetypes and are fine with the default repository.

• Create a new site package doesnt work: because the Afx SiteKickstarter doesnt work and is outdated
  -> removed via TASK: Remove createSitePackage action #5139

[mhsdesign]

okay instead of adding a bunch of notes that the module is fragile and deprecating the site creation like originally proposed in #5440:

we discussed today that we rather only want to offer to create a blank site.

The reason for this is that the site import functionality can hardly be used in a useful way:

• importing is only possible if no blank site has been created yet and if no site import was carried out previously -> basically when the system is new.
• a new system without a site should use the cli to create an initial site as it will be told by the flow setup tool. Now attempting to log in with a previously via cli created user will work but redirect to the neos/content module wich is broken at this time with a raw 500 error - not showing the outer menu anymore. This is a bigger construction site and this behaviour is also this way in Neos 8.

So the only way to get to use the import site functionality is actually by knowing the /neos/administration/sites route and then using the functionality there. This is all very unlikely and we instead agreed that the first site ought to be imported by CLI (rendering following imports currently useless) which means that the site module will continue to exist but only with 'create blank' as an option.