1. Added KeyValueStore.Iterate for implementing the different List, ListV2 etc. implementations. This allows for more efficient use of memory depending on the situation.
2. Implemented an inmemory teststore for running tests. This should allow to replace MockKeyValueStore in most places.
3. Rewrote tests
4. Pulled out logger from bolt implementation so it can be used for all other storage implementations.
5. Fixed multiple things in bolt and redis implementations.
* Don't use url.Parse for bolt paths: filepaths may not be valid URL-s.
* go.mod: update dependencies
* README.md: add Windows instructions
* pkg/overlay: check for the correct path and text in error
* pkg/overlay: fix tests for windows
* pkg/piecestore: make windows tests pass
* pkg/telemetry: skip test, as it doesn't shutdown nicely
* storage/redis: ensure that redis is clean before running tests
