Improve issue & code search (#33860)

Each "indexer" should provide the "search modes" they support by
themselves. And we need to remove the "fuzzy" search for code.

modules/indexer/issues/meilisearch/meilisearch.go

@@ -10,6 +10,7 @@ import (
 	"strconv"
 	"strings"
 
+	"code.gitea.io/gitea/modules/indexer"
 	indexer_internal "code.gitea.io/gitea/modules/indexer/internal"
 	inner_meilisearch "code.gitea.io/gitea/modules/indexer/internal/meilisearch"
 	"code.gitea.io/gitea/modules/indexer/issues/internal"
@@ -35,6 +36,10 @@ type Indexer struct {
 	indexer_internal.Indexer // do not composite inner_meilisearch.Indexer directly to avoid exposing too much
 }
 
+func (b *Indexer) SupportedSearchModes() []indexer.SearchMode {
+	return indexer.SearchModesExactWords()
+}
+
 // NewIndexer creates a new meilisearch indexer
 func NewIndexer(url, apiKey, indexerName string) *Indexer {
 	settings := &meilisearch.Settings{
@@ -230,9 +235,8 @@ func (b *Indexer) Search(ctx context.Context, options *internal.SearchOptions) (
 		limit = 1
 	}
 
-	keyword := options.Keyword
-	if !options.IsFuzzyKeyword {
-		// to make it non fuzzy ("typo tolerance" in meilisearch terms), we have to quote the keyword(s)
+	keyword := options.Keyword // default to match "words"
+	if options.SearchMode == indexer.SearchModeExact {
 		// https://www.meilisearch.com/docs/reference/api/search#phrase-search
 		keyword = doubleQuoteKeyword(keyword)
 	}