Variable query editor (#856)

* refactor: convert module to typescript

* refactor: covert utils to typescript

* variable query editor WIP

* variable editor: fix type error after grafana/ui update

* variable editor: use FormLabel from grafana/ui

* variable editor: refactor

* variable editor: input validation and highlights

* variable editor: fix tests

* variable query: fix backward compatibility with empty queries

* fix linter errors

* variable editor: fix variable replacement in queries

src/datasource-zabbix/types.ts

@@ -0,0 +1,30 @@
+import { SelectableValue } from "@grafana/data";
+
+export interface VariableQueryProps {
+  query: LegacyVariableQuery;
+  onChange: (query: VariableQuery, definition: string) => void;
+  datasource: any;
+  templateSrv: any;
+}
+
+export interface VariableQueryData extends VariableQuery {
+  selectedQueryType: SelectableValue<VariableQueryTypes>;
+  legacyQuery?: string;
+}
+
+export interface VariableQuery {
+  queryType: VariableQueryTypes;
+  group?: string;
+  host?: string;
+  application?: string;
+  item?: string;
+}
+
+export type LegacyVariableQuery = VariableQuery | string;
+
+export enum VariableQueryTypes {
+  Group = 'group',
+  Host = 'host',
+  Application = 'application',
+  Item = 'item',
+}