add csv templating format

public/app/features/templating/specs/template_srv.jest.ts

@@ -107,7 +107,6 @@ describe('templateSrv', function() {
       ]);
     });
 
-
     it('should replace $test with globbed value', function() {
       var target = _templateSrv.replace('this.$test.filters', {}, 'glob');
       expect(target).toBe('this.{value1,value2}.filters');
@@ -261,6 +260,11 @@ describe('templateSrv', function() {
       expect(result).toBe('test');
     });
 
+    it('multi value and csv format should render csv string', function() {
+      var result = _templateSrv.formatValue(['test', 'test2'], 'csv');
+      expect(result).toBe('test,test2');
+    });
+
     it('slash should be properly escaped in regex format', function() {
       var result = _templateSrv.formatValue('Gi3/14', 'regex');
       expect(result).toBe('Gi3\\/14');

public/app/features/templating/template_srv.ts

@@ -115,6 +115,12 @@ export class TemplateSrv {
         }
         return this.distributeVariable(value, variable.name);
       }
+      case 'csv': {
+        if (_.isArray(value)) {
+          return value.join(',');
+        }
+        return value;
+      }
       default: {
         if (_.isArray(value)) {
           return '{' + value.join(',') + '}';