Introduce visibility flag for bootstrap gitlab

Signed-off-by: Viktor Nagy <vnagy@gitlab.com>

internal/flags/gitlab_visibility_test.go

@@ -0,0 +1,47 @@
+/*
+Copyright 2024 The Flux authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package flags
+
+import (
+	"testing"
+)
+
+func TestGitLabVisibility_Set(t *testing.T) {
+	tests := []struct {
+		name      string
+		str       string
+		expect    string
+		expectErr bool
+	}{
+		{"private", "private", "private", false},
+		{"internal", "internal", "internal", false},
+		{"public", "public", "public", false},
+		{"unsupported", "unsupported", "", true},
+		{"default", "", "private", false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var p GitLabVisibility
+			if err := p.Set(tt.str); (err != nil) != tt.expectErr {
+				t.Errorf("Set() error = %v, expectErr %v", err, tt.expectErr)
+			}
+			if str := p.String(); str != tt.expect {
+				t.Errorf("Set() = %v, expect %v", str, tt.expect)
+			}
+		})
+	}
+}