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/bootstrap/index.go

@@ -1,10 +1,5 @@
 package bootstrap
 
-import (
-	"github.com/alist-org/alist/v3/internal/conf"
-	"github.com/alist-org/alist/v3/internal/index"
-)
-
 func InitIndex() {
-	index.Init(&conf.Conf.IndexDir)
+	// TODO init ? Probably not.
 }