cli: move cosigners parsing to a separate function

We have a lot of common code which is shared between `smartcontract` and
`wallet` cli packages. It's convinient to keep it in a separate helper
package in order to avoid functional cli packages dependencies.

cli/cmdargs/parser_test.go

@@ -0,0 +1,54 @@
+package cmdargs
+
+import (
+	"testing"
+
+	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseCosigner(t *testing.T) {
+	acc := util.Uint160{1, 3, 5, 7}
+	testCases := map[string]transaction.Signer{
+		acc.StringLE(): {
+			Account: acc,
+			Scopes:  transaction.CalledByEntry,
+		},
+		"0x" + acc.StringLE(): {
+			Account: acc,
+			Scopes:  transaction.CalledByEntry,
+		},
+		acc.StringLE() + ":Global": {
+			Account: acc,
+			Scopes:  transaction.Global,
+		},
+		acc.StringLE() + ":CalledByEntry": {
+			Account: acc,
+			Scopes:  transaction.CalledByEntry,
+		},
+		acc.StringLE() + ":None": {
+			Account: acc,
+			Scopes:  transaction.None,
+		},
+		acc.StringLE() + ":CalledByEntry,CustomContracts": {
+			Account: acc,
+			Scopes:  transaction.CalledByEntry | transaction.CustomContracts,
+		},
+	}
+	for s, expected := range testCases {
+		actual, err := parseCosigner(s)
+		require.NoError(t, err)
+		require.Equal(t, expected, actual)
+	}
+	errorCases := []string{
+		acc.StringLE() + "0",
+		acc.StringLE() + ":Unknown",
+		acc.StringLE() + ":Global,CustomContracts",
+		acc.StringLE() + ":Global,None",
+	}
+	for _, s := range errorCases {
+		_, err := parseCosigner(s)
+		require.Error(t, err)
+	}
+}