[typescript-angular] add license information for api.base.service.mustache

The new BaseService was added in OpenAPITools#20681, but the license information was not added.

Author: MoritzWeber0

modules/openapi-generator/src/main/resources/typescript-angular/api.base.service.mustache

@@ -1,3 +1,5 @@
+{{>licenseInfo}}
+
 import { HttpHeaders, HttpParams, HttpParameterCodec } from '@angular/common/http';
 import { CustomHttpParameterCodec } from './encoder';
 import { {{configurationClassName}} } from './configuration';