MEL bound `state-trie-migration` (#11639)

* MEL bound state-trie-migration

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* wip

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Add tests

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Use sp_std

Co-authored-by: cheme <emericchevalier.pro@gmail.com>

* Add doc

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Set MaxKeyLen default to 512

Just to be sure that it will work. There is also no real penalty
from over-estimating it.

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Add more doc

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Clippy

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* fmt

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Fix assert_err_with_weight macro

Looks like I'm the only one using it anyway...

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Fix tests that use env macro

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Fix test

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

Co-authored-by: cheme <emericchevalier.pro@gmail.com>