At least with LPC55S69's default TDBStore configuration it's
impossible to run storage Greentea tests without exhausting the
memory reserved for storing keys.
Fixes an issue where number of keys were removed based on number of
threads which didn't have anything to do with the test case.
Fixes an issue where number of keys were assumed to be constant
but variable number was used for configuration.
Implement the following:
KVStore base class
TDBStore class
FileSystemStore class
SecureStore class
Global APIs
Configuration framework
Design documentation