[RFC] including base xbps cache in the iso and setup scripts

Inizia leggendo installer.sh.in intorno all’elenco delle eccezioni collegato e build-x86-images.sh per l’attuale flusso di configurazione della ISO. Traccia le differenze tra le installazioni locali e quelle di rete, quindi valuta come script di configurazione condivisi e una cache xbps di base potrebbero supportare entrambi i percorsi. Il lavoro sarà considerato completo quando sarà disponibile un piano concreto di progettazione e implementazione che affronti le dimensioni della cache, la selezione dei pacchetti e la personalizzazione separata della ISO.

Currently we are copying the live system to the target when Local source is selected. This means both systems have to be exactly the same and we maintain a list of exceptions for what should not be copied to the target system in the installer (xmirror, xtools-minimal, sudoers, some configs, etc.).

Ideally we would want the iso and the target system to be created by the same code, but also allow customizing only the iso with additional packages or files. This can done by:

1. including xbps cache for the base system and letting local install be the same as network install, but use that cache instead of remote repositories
2. move the iso setup logic from build-x86-images.sh to individual setup scripts. These setup scripts would be included in the iso and used both for creating the iso and installing the target system

Disadvantages:

• people won't be able to install xfce without network anymore (because including whole xfce xbps cache would create a very big iso)
• bigger isos (because we would have to include the base system xbps cache which is 340-350MB, current base isos have ~650MB, so this would increase their size to ~1GB, we could also have a way to create smaller netinstall isos without cache)

Advantages:

• high flexibility - people can easily create their own iso spins just by copying one setup file
• cleaner code (we won't need a list of exceptions to prevent some packages or files from getting installed)
• less bugs because setting up the iso is done with the same code as the final system, but the setups are separate and the same code is used for both netinstall and local install (for example currently, the local install installs cryptsetup, lvm2 and mdadm to the local system for no reason, but netinstall doesn't)
• ability to install the xfce system even from the base iso (when network is available)