Migrate to one stamp per chain

[PabloCastellano]

At the moment we are using one single stamp to store all blobs and we are going to migrate to a one-stamp-per-chain approach.

Pros of using one stamp per chain:

• Allow to trustlessly crowdfund blobs storage per chain.
• Having one stamp per chain increases flexibility
• If for some reason we want the stamp to expire, all the data would be lost, not just some parts of it.

Cons:

• We will reach smaller total capacity for content addressed content
• A bit more maintenance is required

TODO

• This change requires knowing the batch id that must be used for each chain. We can generate the stamp beforehand and set the batch id in a new variable.
• Add another variable to configure redundancy level (we can default it to 0)
• Decide what redundancy level we want to use on (medium increases costs by 7,6% while strong increases 19,6%). Same for all chains including testnets?
• Implement erasure coding (Reupload blobs to swarm using the erasure coding feature #352) before, to avoid reuploading twice.