Add VHIVE_REPO and LOADER_REPO to setup script config

[mghgm]

Summary

Adds a separate variable for VHIVE_REPO and LOADER_REPO in ./scripts/setup/setup.cfg to be able to use private repos in setup script (fixes vhive-serverless/invitro#538).

Implementation Notes :hammer_and_pick:

• Briefly outline the overall technical solution. If necessary, identify talking points where the reviewer's attention should be drawn to.

In scripts under setup directory, next to every VHIVE_BRANCH and LOADER_BRANCH, repository urls are replaced with a proper variable which has already defined in setup.cfg.

External Dependencies :four_leaf_clover:

• N/A

Breaking API Changes :warning:

• N/A

[leokondrashov]

@cvetkovic Please take a look