Add option to overwrites tags option with values specified in an file (#62)

Reviewed-on: https://codeberg.org/woodpecker-plugins/docker-buildx/pulls/62
Reviewed-by: qwerty287 <qwerty287@noreply.codeberg.org>

utils/lamda.go

@@ -0,0 +1,9 @@
+package utils
+
+func Map[T any](in []T, fn func(T) T) []T {
+	out := in
+	for i := range in {
+		out[i] = fn(out[i])
+	}
+	return out
+}

utils/lamda_test.go

@@ -0,0 +1,18 @@
+package utils
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMap(t *testing.T) {
+	ints := []int{1, 2, 3, 4}
+	ints = Map(ints, func(i int) int { return i * 10 })
+	assert.EqualValues(t, []int{10, 20, 30, 40}, ints)
+
+	sl := []string{"a ", "b", " c"}
+	sl = Map(sl, func(s string) string { return "#" + strings.TrimSpace(s) })
+	assert.EqualValues(t, []string{"#a", "#b", "#c"}, sl)
+}