Cache Presubmit and Gerrit data to serve in the switch mode API.

A test mode can be cached with a combination of three values:
1. golden watcher, 2. download client, 3.goldens_list.
Not all are required all the time.
Presubmit -> 1 and 2.
Gerrit -> 3.
Rest all -> 1, 3(optional).
I created a separate class called TestEntity which encapsulates these attributes and helps in caching the test mode data.

Bug: b/433215682
Test: Manual
Flag: None
Change-Id: I1e43fa6419db4ef5f8ee051a85d35fb8d87884b0
4 files changed