[TASK] Clean up storage transactions

[shurwit]

Description

Currently transactions are implemented within the storage adapter functions. They are also often used unnecessarily or improperly (eg. with a single operation, with some operations missing context)

Acceptance Criteria

As originally described here rokwire/core-building-block#285. the storage adapter should expose individual storage operations and multi-stage transactions should be composed in the core package passing the storage.TransactionContext to each storage adapter function. Any unnecessary or improperly used transactions should be fixed or removed as appropriate.