Create performance load tests for backend and frontend

[mutambaraf]

Set up performance test of the new proposal system backend and frontend. The performance tests will be written in grafana K6 https://grafana.com/docs/k6/latest .The test will initially run as a jerkins job which will run at midnight when the system will not be under much load.

• [x] Set up a new repo for the performance tests.
• [x] Create the performance tests scripts and configure thresholds.
• [x] Create a Jenkins job that run against develop.
• [x] Set load tests to user the biggest agent but adding a tag.
• [x] Update k6 to directly interact with oracle database and remove the need of user setup server.
• [x] Update all documentations.
• [ ] Potentially ship metrics to centralised logging

[mutambaraf]

Documentation added by https://github.com/UserOfficeProject/user-office-proposal-performance-tests/pull/1