Migrate `pallet-collective` to the new pallet attribute macro (#9115)

* Migrate pallet-collective to the new pallet attribute macro

Signed-off-by: koushiro <[email protected]>

* Add migrations

Signed-off-by: koushiro <[email protected]>

* some nits

Signed-off-by: koushiro <[email protected]>

* fix some indent

Signed-off-by: koushiro <[email protected]>

* Fix

Signed-off-by: koushiro <[email protected]>

* Fix

Signed-off-by: koushiro <[email protected]>

* fmt

* fix migration

* fix migration

* fmt

* finally fix migration

* keep the storages public as they were

* Some nits

Signed-off-by: koushiro <[email protected]>

* Fix migration

Signed-off-by: koushiro <[email protected]>

* Fix migration and Add test

Signed-off-by: koushiro <[email protected]>

* Some nits

Signed-off-by: koushiro <[email protected]>

* improve test

Signed-off-by: koushiro <[email protected]>

* improve test

Signed-off-by: koushiro <[email protected]>

* Revert the changes of membership

Signed-off-by: koushiro <[email protected]>

* Some nits

Signed-off-by: koushiro <[email protected]>

* Fix test

Signed-off-by: koushiro <[email protected]>

* Fix test

Signed-off-by: koushiro <[email protected]>

* Some nits

Signed-off-by: koushiro <[email protected]>

* don't assert that there is something at the old prefix in the pre-migrate

Signed-off-by: koushiro <[email protected]>

* cargo fmt

Co-authored-by: thiolliere <[email protected]>