Improve inactive fund tracking (#6471)

* Improve inactive fund tracking

* Docs

* Introduce the re-migration code

* Bump

* Update runtime/kusama/src/lib.rs

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Update runtime/common/src/crowdloan/migration.rs

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Update runtime/common/src/crowdloan/migration.rs

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Grumbles

* Apply comments suggestions from code review

Co-authored-by: Bastian Köcher <info@kchr.de>

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: muharem <ismailov.m.h@gmail.com>
Co-authored-by: Bastian Köcher <info@kchr.de>
Co-authored-by: parity-processbot <>