TemplateSrv: exposing a function to detect if a target contains a template (#45214)

* exposing a function to check if a target contains variables.

* fixed tests.

* renamed function

* updated betterer result.

packages/grafana-runtime/src/services/templateSrv.ts

@@ -17,6 +17,11 @@ export interface TemplateSrv {
    * Replace the values within the target string.  See also {@link InterpolateFunction}
    */
   replace(target?: string, scopedVars?: ScopedVars, format?: string | Function): string;
+
+  /**
+   * Checks if a target contains template variables.
+   */
+  containsTemplate(target?: string): boolean;
 }
 
 let singletonInstance: TemplateSrv;