Cardano Updates

Fix link in metadata.md

You got an error: "curl: (52) Empty reply from server" if you follow the tutorial completely.

This reverts commit 28aa0f50699f0cdcc5d84bd9881daa8101a8ee06.

This has a few small benefits

  * define's TxMeasure `leq` via the pointwise minimum

  * removes the redundancy of specifying the `pointwiseMin` method per ledger
    instead of per 'Measure'

  * avoids the need for type applications, which let's us re-use the <=
    operator

and two large benefits

  * creates an opportunity for more use of deriving

  * the top-bounded meet-semilattice foundation means that `noOverrides` can be
    implemented as `top`; we don't need it to be a function from the (dynamic!)
    ledger limits anymore.

We had previously decided on a function because it made it trivial to override
only parts of the ledger-derived capacity. However, we simplified the override
representation (no more `NP`) and a interface that uses the static `top`
instead of the dynamic "current ledger capacity" is more appropriate for a
interface used for static configuration.

In other words, the function space was "too big" for the following reasons.

  * in practice, these values are parsed from a file, and I doubt the Node Team
    wants to parse functions anytime soon

  * we do not anticipate the node operator wanting to vary their override
    depending on the ledger capacity

The 'Measure' class's lattice semantics let us remove the function space
without losing any convenience.

Co-authored-by: Pawel Szulc <[email protected]>

chain-evm: implement basic storage backend