[#193] pkg/container: Wrap container structure with SDK functions

All setters and getters should work with SDK types.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/container/attribute.go

@@ -0,0 +1,56 @@
+package container
+
+import (
+	"github.com/nspcc-dev/neofs-api-go/v2/container"
+)
+
+type (
+	Attribute  container.Attribute
+	Attributes []*Attribute
+)
+
+func NewAttribute() *Attribute {
+	return NewAttributeFromV2(new(container.Attribute))
+}
+
+func (a *Attribute) SetKey(v string) {
+	(*container.Attribute)(a).SetKey(v)
+}
+
+func (a *Attribute) SetValue(v string) {
+	(*container.Attribute)(a).SetValue(v)
+}
+
+func (a *Attribute) Key() string {
+	return (*container.Attribute)(a).GetKey()
+}
+
+func (a *Attribute) Value() string {
+	return (*container.Attribute)(a).GetValue()
+}
+
+func NewAttributeFromV2(v *container.Attribute) *Attribute {
+	return (*Attribute)(v)
+}
+
+func (a *Attribute) ToV2() *container.Attribute {
+	return (*container.Attribute)(a)
+}
+
+func NewAttributesFromV2(v []*container.Attribute) Attributes {
+	attrs := make(Attributes, 0, len(v))
+	for i := range v {
+		attrs = append(attrs, NewAttributeFromV2(v[i]))
+	}
+
+	return attrs
+}
+
+func (a Attributes) ToV2() []*container.Attribute {
+	attrs := make([]*container.Attribute, 0, len(a))
+	for i := range a {
+		attrs = append(attrs, a[i].ToV2())
+	}
+
+	return attrs
+}