Improve grep search (#30843)

Reduce the context line number to 1, make "git grep" search respect the
include/exclude patter, and fix #30785

routers/web/repo/search_test.go

@@ -0,0 +1,19 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/test"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIndexSettingToGitGrepPathspecList(t *testing.T) {
+	defer test.MockVariableValue(&setting.Indexer.IncludePatterns, setting.IndexerGlobFromString("a"))()
+	defer test.MockVariableValue(&setting.Indexer.ExcludePatterns, setting.IndexerGlobFromString("b"))()
+	assert.Equal(t, []string{":(glob)a", ":(glob,exclude)b"}, indexSettingToGitGrepPathspecList())
+}