[#388] *: Remove nil check from setters

I knew one day `sed` would save me an hour of manual work:
```
sed -i -n -e '
s/) Set/) Set/
p
t setter
b end
:setter
    n
    s/nil/nil/
    t hasif
    p
    b end
    :hasif
        n
        :loop
        p
        n
        s/}/}/
        t end
        b loop
        :end
' $@
goimports -w $@
```

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

netmap/grpc/types.go

@@ -4,142 +4,102 @@ import refs "github.com/nspcc-dev/neofs-api-go/v2/refs/grpc"
 
 // SetReplicas of placement policy.
 func (m *PlacementPolicy) SetReplicas(v []*Replica) {
-	if m != nil {
-		m.Replicas = v
-	}
+	m.Replicas = v
 }
 
 // SetContainerBackupFactor of placement policy.
 func (m *PlacementPolicy) SetContainerBackupFactor(v uint32) {
-	if m != nil {
-		m.ContainerBackupFactor = v
-	}
+	m.ContainerBackupFactor = v
 }
 
 // SetSelectors of placement policy.
 func (m *PlacementPolicy) SetSelectors(v []*Selector) {
-	if m != nil {
-		m.Selectors = v
-	}
+	m.Selectors = v
 }
 
 // SetFilters of placement policy.
 func (m *PlacementPolicy) SetFilters(v []*Filter) {
-	if m != nil {
-		m.Filters = v
-	}
+	m.Filters = v
 }
 
 // SetSubnetID sets ID of subnet.
 func (m *PlacementPolicy) SetSubnetID(v *refs.SubnetID) {
-	if m != nil {
-		m.SubnetId = v
-	}
+	m.SubnetId = v
 }
 
 // SetName of placement filter.
 func (m *Filter) SetName(v string) {
-	if m != nil {
-		m.Name = v
-	}
+	m.Name = v
 }
 
 // SetKey of placement filter.
 func (m *Filter) SetKey(v string) {
-	if m != nil {
-		m.Key = v
-	}
+	m.Key = v
 }
 
 // SetOperation of placement filter.
 func (m *Filter) SetOp(v Operation) {
-	if m != nil {
-		m.Op = v
-	}
+	m.Op = v
 }
 
 // SetValue of placement filter.
 func (m *Filter) SetValue(v string) {
-	if m != nil {
-		m.Value = v
-	}
+	m.Value = v
 }
 
 // SetFilters sets sub-filters of placement filter.
 func (m *Filter) SetFilters(v []*Filter) {
-	if m != nil {
-		m.Filters = v
-	}
+	m.Filters = v
 }
 
 // SetName of placement selector.
 func (m *Selector) SetName(v string) {
-	if m != nil {
-		m.Name = v
-	}
+	m.Name = v
 }
 
 // SetCount of nodes of placement selector.
 func (m *Selector) SetCount(v uint32) {
-	if m != nil {
-		m.Count = v
-	}
+	m.Count = v
 }
 
 // SetAttribute of nodes of placement selector.
 func (m *Selector) SetAttribute(v string) {
-	if m != nil {
-		m.Attribute = v
-	}
+	m.Attribute = v
 }
 
 // SetFilter of placement selector.
 func (m *Selector) SetFilter(v string) {
-	if m != nil {
-		m.Filter = v
-	}
+	m.Filter = v
 }
 
 // SetClause of placement selector.
 func (m *Selector) SetClause(v Clause) {
-	if m != nil {
-		m.Clause = v
-	}
+	m.Clause = v
 }
 
 // SetCount of object replica.
 func (m *Replica) SetCount(v uint32) {
-	if m != nil {
-		m.Count = v
-	}
+	m.Count = v
 }
 
 // SetSelector of object replica.
 func (m *Replica) SetSelector(v string) {
-	if m != nil {
-		m.Selector = v
-	}
+	m.Selector = v
 }
 
 // SetKey sets key to the node attribute.
 func (m *NodeInfo_Attribute) SetKey(v string) {
-	if m != nil {
-		m.Key = v
-	}
+	m.Key = v
 }
 
 // SetValue sets value of the node attribute.
 func (m *NodeInfo_Attribute) SetValue(v string) {
-	if m != nil {
-		m.Value = v
-	}
+	m.Value = v
 }
 
 // SetParent sets value of the node parents.
 func (m *NodeInfo_Attribute) SetParents(v []string) {
-	if m != nil {
-		m.Parents = v
-	}
+	m.Parents = v
 }
 
 // SetAddress sets node network address.
@@ -151,58 +111,42 @@ func (m *NodeInfo) SetAddress(v string) {
 
 // SetAddresses sets list of network addresses of the node.
 func (m *NodeInfo) SetAddresses(v []string) {
-	if m != nil {
-		m.Addresses = v
-	}
+	m.Addresses = v
 }
 
 // SetPublicKey sets node public key in a binary format.
 func (m *NodeInfo) SetPublicKey(v []byte) {
-	if m != nil {
-		m.PublicKey = v
-	}
+	m.PublicKey = v
 }
 
 // SetAttributes sets list of the node attributes.
 func (m *NodeInfo) SetAttributes(v []*NodeInfo_Attribute) {
-	if m != nil {
-		m.Attributes = v
-	}
+	m.Attributes = v
 }
 
 // SetState sets node state.
 func (m *NodeInfo) SetState(v NodeInfo_State) {
-	if m != nil {
-		m.State = v
-	}
+	m.State = v
 }
 
 // SetCurrentEpoch sets number of the current epoch.
 func (x *NetworkInfo) SetCurrentEpoch(v uint64) {
-	if x != nil {
-		x.CurrentEpoch = v
-	}
+	x.CurrentEpoch = v
 }
 
 // SetMagicNumber sets magic number of the sidechain.
 func (x *NetworkInfo) SetMagicNumber(v uint64) {
-	if x != nil {
-		x.MagicNumber = v
-	}
+	x.MagicNumber = v
 }
 
 // SetMsPerBlock sets MillisecondsPerBlock network parameter.
 func (x *NetworkInfo) SetMsPerBlock(v int64) {
-	if x != nil {
-		x.MsPerBlock = v
-	}
+	x.MsPerBlock = v
 }
 
 // SetNetworkConfig sets NeoFS network configuration.
 func (x *NetworkInfo) SetNetworkConfig(v *NetworkConfig) {
-	if x != nil {
-		x.NetworkConfig = v
-	}
+	x.NetworkConfig = v
 }
 
 // FromString parses Clause from a string representation,
@@ -246,21 +190,15 @@ func (x *NodeInfo_State) FromString(s string) bool {
 
 // SetKey sets parameter key.
 func (x *NetworkConfig_Parameter) SetKey(v []byte) {
-	if x != nil {
-		x.Key = v
-	}
+	x.Key = v
 }
 
 // SetValue sets parameter value.
 func (x *NetworkConfig_Parameter) SetValue(v []byte) {
-	if x != nil {
-		x.Value = v
-	}
+	x.Value = v
 }
 
 // SetParameters sets NeoFS network parameters.
 func (x *NetworkConfig) SetParameters(v []*NetworkConfig_Parameter) {
-	if x != nil {
-		x.Parameters = v
-	}
+	x.Parameters = v
 }