Make app-gradle-plugin configuration cache compatible

Make app-gradle-plugin configuration cache compatible. [Configuration cache](https://docs.gradle.org/current/userguide/configuration_cache.html) is about to ship stable. Enabling it currently causes GCP gradle plugin to fail in multiple ways
```
3 problems were found reusing the configuration cache.
- Task `:appengineDeploy` of type `com.google.cloud.tools.gradle.appengine.core.DeployTask`: cannot deserialize object of type 'org.gradle.api.Project' as these are not supported with the configuration cache.
See https://docs.gradle.org/7.6/userguide/configuration_cache.html#config_cache:requirements:disallowed_types
- Task `:appengineStage` of type `com.google.cloud.tools.gradle.appengine.appyaml.StageAppYamlTask`: cannot deserialize object of type 'org.gradle.api.Project' as these are not supported with the configuration cache.
See https://docs.gradle.org/7.6/userguide/configuration_cache.html#config_cache:requirements:disallowed_types
- Task `:downloadCloudSdk` of type `com.google.cloud.tools.gradle.appengine.core.DownloadCloudSdkTask`: invocation of 'Task.project' at execution time is unsupported.
See https://docs.gradle.org/7.6/userguide/configuration_cache.html#config_cache:requirements:use_project_during_execution
```