Feat: approvers are now using a non-attackable datastructure

go.mod

go.sum

packages/binary/tangle/model/approver/approver.go

packages/binary/tangle/model/approver/cached_approver.go

packages/binary/tangle/model/approvers_old/approvers.go

...ges/binary/tangle/model/approvers_old/cached_approvers.go

.../model/transaction/payload/valuetransfer/valuetransfer.go

packages/binary/tangle/tangle.go

packages/binary/tangle/tangle_test.go

packages/binary/types/empty.go

packages/ledgerstate/reality/id_list.go

packages/ledgerstate/reality/id_set.go