Changes and docs to system partitioning

[mauromorales]

From the discussion in planning we decided that no matter how we allow the user to define the image and partition sizes, they would always need to understand what the implications are, which means they should be reading our docs. Having said that, if they are already reading the docs, if we explain clearly enough, any solution is acceptable.

So let's do this:

• We allow the user to set both image sizes and partition sizes
• If the settings are not sane (e.g. the images won't fit in the partition in every case, including upgrades) then we fail with an error
• If the user only sets images size, we do automated calculations for partitions
• For persistent and oem partitions we don't have to check much, maybe just a minimum for oem to fit the files we put there.
• We document everything clearly

Originally posted by @jimmykarily in https://github.com/kairos-io/kairos/issues/2151#issuecomment-1903595690

For the documentation, see the description of the previous ticket https://github.com/kairos-io/kairos/issues/2151#issue-2086456287

[mauromorales]

we forgot to discuss about the other attributes e.g. label, which if "personalized" will cause issues

[mauromorales]

the following parameters, are "configurable" according to the docs

https://github.com/kairos-io/kairos-agent/blob/main/pkg/config/spec.go#L145-L147

But it's not really implemented. In some cases like the FS maybe it makes sense, but in others like the label, this would be disruptive to how Kairos works atm. IMO we should either remove that from the docs, or at least make a note that this is not possible and point to a card which describes the implementation, WDYT @kairos-io/maintainers

[jimmykarily]

This might introduce more options that need to be documented: https://github.com/kairos-io/kairos/issues/2281 We don't necessarily have to do them all in one step, but just linking it here for reference.