Add v2 version to go module name

Replace all elements from `v2` to root directory.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

accounting/grpc/types.go

@@ -0,0 +1,15 @@
+package accounting
+
+// SetValue sets value of the decimal number.
+func (m *Decimal) SetValue(v int64) {
+	if m != nil {
+		m.Value = v
+	}
+}
+
+// SetPrecision sets precision of the decimal number.
+func (m *Decimal) SetPrecision(v uint32) {
+	if m != nil {
+		m.Precision = v
+	}
+}