[Elephant] Changed type field to modificationType in ModifyMultisigAccount

[evias]

With elephant-2 released, the field named type in ModifyMultisigAccountTransaction was changed to modificationType

Source: https://github.com/nemtech/catapult-server/commit/835def4330cfe346bc5f48ee444c3048e08e92fd#diff-f94bbe5632d19a21229ac20440c895dcR34

This may introduce inconsistencies with REST schemas (DTOs updates?) or SDK models.

Similarly to this one, in AccountRestrictions, the type field got renamed by restrictionType

• https://github.com/nemtech/catapult-server/commit/835def4330cfe346bc5f48ee444c3048e08e92fd#diff-9fd9402daeb67e1c4b610dc8edfa32feR41