feat: feature list all accounts on main get call.

[venkat-ecov-dev]

Related Issue(s):
##15
##16

Proposed Changes:

1. Feature to return list of accounts on main get api endpoint

PR Checklist:

• [x ] This PR is made against the dev branch (all proposed changes except releases should be against dev, not main).
• [ x] This PR has no breaking changes.
• [ x] This PR contains only one commit.
• [ x] I have updated or added new tests to cover the changes in this PR.
• [ x] All tests are passing.
• [ x] This PR affects the Source Cooperative Frontend & API,
  and I have opened issue/PR #XXX to track the change.

[amit-ecovoice]

I believe this change also require replacement health-check endpoint and this change has to go along with Load balancer health check url change . Please validate.