ensure the existence of @fireproof/encrypted-blockstore

From the 0.19 version we abandon the
https://www.npmjs.com/package/@fireproof/encrypted-blockstore
@jchris wants the SEO of this "sub" aspect of the core to be visible.
So we have to ensure that with every /core release we also have a encrypted-blockstore is released.
We should use the same approach as use-fireproof package which proxied the core.
And to ensure that this sub-functionality is working we need to build a test from the docs/readme,
and update the readme accordingly.