Show job hierarchy in the TG dashboard.

[kasunbg]

Description:
Right now, the TG dashboard has a flat hierarchy -

It is not aware of the folder-based hierarchy that we have - https://github.com/wso2/testgrid-job-configs/tree/devenv/team-tg

This is an issue for us. Why?

1. If two folders had the same job-name, then they conflict. In the TG dashboard we will show both jobs as a single job
2. The UI become cluttered.
3. Teams cannot easily find the jobs they own.

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So, we need job hierarchy shown in the dashboard. What would it look like?

It may look like following:

(I created this by modifying the DOM via Chrome Inspect Element view! :) )