Issue search support elasticsearch (#9428)

* Issue search support elasticsearch

* Fix lint

* Add indexer name on app.ini

* add a warnning on SearchIssuesByKeyword

* improve code

vendor/github.com/olivere/elastic/v7/search_queries_wildcard.go

@@ -0,0 +1,81 @@
+// Copyright 2012-present Oliver Eilhard. All rights reserved.
+// Use of this source code is governed by a MIT-license.
+// See http://olivere.mit-license.org/license.txt for details.
+
+package elastic
+
+// WildcardQuery matches documents that have fields matching a wildcard
+// expression (not analyzed). Supported wildcards are *, which matches
+// any character sequence (including the empty one), and ?, which matches
+// any single character. Note this query can be slow, as it needs to iterate
+// over many terms. In order to prevent extremely slow wildcard queries,
+// a wildcard term should not start with one of the wildcards * or ?.
+// The wildcard query maps to Lucene WildcardQuery.
+//
+// For more details, see
+// https://www.elastic.co/guide/en/elasticsearch/reference/7.0/query-dsl-wildcard-query.html
+type WildcardQuery struct {
+	name      string
+	wildcard  string
+	boost     *float64
+	rewrite   string
+	queryName string
+}
+
+// NewWildcardQuery creates and initializes a new WildcardQuery.
+func NewWildcardQuery(name, wildcard string) *WildcardQuery {
+	return &WildcardQuery{
+		name:     name,
+		wildcard: wildcard,
+	}
+}
+
+// Boost sets the boost for this query.
+func (q *WildcardQuery) Boost(boost float64) *WildcardQuery {
+	q.boost = &boost
+	return q
+}
+
+func (q *WildcardQuery) Rewrite(rewrite string) *WildcardQuery {
+	q.rewrite = rewrite
+	return q
+}
+
+// QueryName sets the name of this query.
+func (q *WildcardQuery) QueryName(queryName string) *WildcardQuery {
+	q.queryName = queryName
+	return q
+}
+
+// Source returns the JSON serializable body of this query.
+func (q *WildcardQuery) Source() (interface{}, error) {
+	// {
+	//	"wildcard" : {
+	//		"user" : {
+	//      "wildcard" : "ki*y",
+	//      "boost" : 1.0
+	//    }
+	// }
+
+	source := make(map[string]interface{})
+
+	query := make(map[string]interface{})
+	source["wildcard"] = query
+
+	wq := make(map[string]interface{})
+	query[q.name] = wq
+
+	wq["wildcard"] = q.wildcard
+
+	if q.boost != nil {
+		wq["boost"] = *q.boost
+	}
+	if q.rewrite != "" {
+		wq["rewrite"] = q.rewrite
+	}
+	if q.queryName != "" {
+		wq["_name"] = q.queryName
+	}
+
+	return source, nil
+}