e2e test setup. cc @hanahmily @peng-yongsheng @IanCao @zhaoyuguang @JaredTan95 

# e2e test case
One single standalone Spring service, accessing H2 database. This service has been installed the agent. 
OAP runs in single mode with H2 storage too.

The e2e test will verify the results through GraphQL query
1. Traces exist.
2. Service/Service Instance/Endpoint exist and have expected metrics.
3. Topology exists and match expected.