Add FolderUID for library elements (#79572)

* Add FolderUID in missing places for libraryelements

* Add migration for FolderUID in library elements table

* Add Folder UIDs tolibrary panels

* Adjust dashboard import with folder uid

* Fix lint

* Rename back FolderUID to UID

* Remove default

* Check if folderUID is nil

* Add unique indes on org_id,folder_uid,name and kind

* Update pkg/services/libraryelements/database.go

Co-authored-by: Sofia Papagiannaki <1632407+papagian@users.noreply.github.com>

* Fix folder integration test, with unique index on library elements

* Make folder uids nullable and rewrite migration query

* Use dashboard uid instead of folder_uid

* Adjust test

---------

Co-authored-by: Sofia Papagiannaki <1632407+papagian@users.noreply.github.com>

pkg/services/libraryelements/model/model.go

@@ -20,6 +20,7 @@ type LibraryElement struct {
 	OrgID int64 `xorm:"org_id"`
 	// Deprecated: use FolderUID instead
 	FolderID    int64  `xorm:"folder_id"`
+	FolderUID   string `xorm:"folder_uid"`
 	UID         string `xorm:"uid"`
 	Name        string
 	Kind        int64
@@ -41,6 +42,7 @@ type LibraryElementWithMeta struct {
 	OrgID int64 `xorm:"org_id"`
 	// Deprecated: use FolderUID instead
 	FolderID    int64  `xorm:"folder_id"`
+	FolderUID   string `xorm:"folder_uid"`
 	UID         string `xorm:"uid"`
 	Name        string
 	Kind        int64
@@ -53,7 +55,6 @@ type LibraryElementWithMeta struct {
 	Updated time.Time
 
 	FolderName          string
-	FolderUID           string `xorm:"folder_uid"`
 	ConnectedDashboards int64
 	CreatedBy           int64
 	UpdatedBy           int64
@@ -217,13 +218,14 @@ type GetLibraryElementCommand struct {
 
 // SearchLibraryElementsQuery is the query used for searching for Elements
 type SearchLibraryElementsQuery struct {
-	PerPage          int
-	Page             int
-	SearchString     string
-	SortDirection    string
-	Kind             int
-	TypeFilter       string
-	ExcludeUID       string
+	PerPage       int
+	Page          int
+	SearchString  string
+	SortDirection string
+	Kind          int
+	TypeFilter    string
+	ExcludeUID    string
+	// Deprecated: use FolderFilterUIDs instead
 	FolderFilter     string
 	FolderFilterUIDs string
 }