feat: multiple search indexes (#2514)

* refactor: abstract search interface

* wip: ~

* fix cycle import

* objs update hook

* wip: ~

* Delete search/none

* auto update index while cache changed

* db searcher

TODO: bleve init issue

cannot open index, metadata missing

* fix size type

why float64??

* fix typo

* fix nil pointer using

* api adapt ui

* bleve: fix clear & change struct

internal/search/searcher/searcher.go

@@ -0,0 +1,29 @@
+package searcher
+
+import (
+	"context"
+
+	"github.com/alist-org/alist/v3/internal/model"
+)
+
+type Config struct {
+	Name       string
+	AutoUpdate bool
+}
+
+type Searcher interface {
+	// Config of the searcher
+	Config() Config
+	// Search specific keywords in specific path
+	Search(ctx context.Context, req model.SearchReq) ([]model.SearchNode, int64, error)
+	// Index obj with parent
+	Index(ctx context.Context, parent string, obj model.Obj) error
+	// Get by parent
+	Get(ctx context.Context, parent string) ([]model.SearchNode, error)
+	// Del with prefix
+	Del(ctx context.Context, prefix string) error
+	// Release resource
+	Release(ctx context.Context) error
+	// Clear all index
+	Clear(ctx context.Context) error
+}