* Fixed logic of the storage migration to triple reference counting. The previous behaviour made it impossible for any chain not already upgraded to dual reference counting to upgrade the runtime.

* +Removed the on_runtime_upgrade() function from frame-system.
+Removed the specific migration .anciallaries from the frame-system pallet level.
+Introducted a new module that hosts self-contained ancillary functions and logic to perform the storage migration. The current logic attempts to infer the state of the storage based on whether or not a given migration can be conducted.

* Formatting.

* + Removed specific AccountData struct. AccountData must now be provided during the runtime implementation of the trait V2ToV3.
+ Removed apply function.
+ Made the individual translation function self-sufficient.

* + Removed unused decorators.