* Re-model persistent database access
why:
Storage slots healing just run on the wrong sub-trie (i.e. the wrong
key mapping). So get/put and bulk functions now use the definitions
in `snapdb_desc` (earlier there were some shortcuts for `get()`.)
* Fixes: missing return code, typo, redundant imports etc.
* Remove obsolete debugging directives from `worker_desc` module
* Correct failing unit tests for storage slots trie inspection
why:
Some pathological cases for the extended tests do not produce any
hexary trie data. This is rightly detected by the trie inspection
and the result checks needed to adjusted.
c0d580715e