yaml: move common_data inside the build directory

[rshym]

All common data should be kept inside the build folder.

[Deedone]

I strongly disagree with the statement that it is better to build with separate caches. As we frequently build multiple images that are very similar to each other, removing the shared cache can worsen build times a lot without giving any clear benefit. I propose to keep it but place it at a new location similar to how downloads dir is moved.

Alternatively, if we really want to do clean builds, it would be nice to at least add moulin feature to automatically place the user's site.conf in every build directory.

[rshym]

I strongly disagree with the statement that it is better to build with separate caches.

After reading related discussions I now agree with your point regarding state caches.
So, this PR now moves common_data inside the build directory, so all build-related stuff is created in the place, that is expected by the user.

[Deedone]

Nice Acked-by: Mykyta Poturai <[email protected]>

[rshym]

Ack is added.
Ready to be merged.