Expose folder UID in dashboards API response (#33991)

* expose folder UID in dashboards API response, import dashboards into folders by folder UID

* handle bad folder UID as 400 error

* 12591:Add tests for request with folderUid

* Use more descriptive error status for missing folders

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

* return 400 when folder id is missing

* put error checking in the right place this time

* mention folderUid in the docs

* Clarify usage of folderUid and folderId when both present

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

* Capitalise UID

Co-authored-by: achatterjee-grafana <70489351+achatterjee-grafana@users.noreply.github.com>

* mention folder UID in the metadata for a GET response

Co-authored-by: Ida Furjesova <ida.furjesova@grafana.com>
Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>
Co-authored-by: achatterjee-grafana <70489351+achatterjee-grafana@users.noreply.github.com>

pkg/api/dtos/dashboard.go

@@ -26,6 +26,7 @@ type DashboardMeta struct {
 	HasAcl                bool      `json:"hasAcl"`
 	IsFolder              bool      `json:"isFolder"`
 	FolderId              int64     `json:"folderId"`
+	FolderUid             string    `json:"folderUid"`
 	FolderTitle           string    `json:"folderTitle"`
 	FolderUrl             string    `json:"folderUrl"`
 	Provisioned           bool      `json:"provisioned"`