Cardano Updates

Previously the QLS test spent half of its search space on making sure we
get coverage for using operations at two different table types. While it
is important to get this coverage, we do not need to divide our search
space in half to achieve it. That search space can be better spent on
longer sequences of actions on fewer tables that can have sharing and
thus interesting interactions.

So we move the {Key,Value,Blob}{1,2} types into the unit test module,
and do a simple unit test where we create, insert, snapshot and restore
tables of two different types.

And we also simplify the QLS test to use a single set of key,value,blob
types.

* mithril-aggregator from `0.5.87` to `0.5.88`
* mithril-common from `0.4.72` to `0.4.73`
* mithril-signer from `0.2.202` to `0.2.203`

Add examples for some types

This will allow to return the latest chain point known by the cardano
block scanner.
Else we only know it when there's a roll foward.

This fix the issue of importing when there's no transactions to store in
a large range of blocks:
* Instead of always using the database to get the start point the db is
  only used for the first chunk.
* For subsequent call the last chain point polled by the streamer is
  used.

* mithril-aggregator from `0.5.86` to `0.5.87`
* mithril-common from `0.4.72` to `0.4.73`
* mithril-signer from `0.2.202` to `0.2.203`