Fix HMI PTU process when using symlinks with Generic HMI

[jacobkeeler]

Testing Plan

• [x] I have verified that I have not introduced new warnings in this PR (or explain why below)
• [x] I have tested this PR against Core and verified behavior (if applicable, if not applicable, explain why below).

Core Tests

Test HMI PTU when running the backend server from a symlinked directory (ln -s path/to/generic_hmi && cd ./generic_hmi && bash deploy_server.sh)

Core version / branch / commit hash / module tested against: develop Proxy+Test App name / version / branch / commit hash / module tested against: RPC builder app JS (master)

Summary

Changes directory check in backend server from abspath to realpath so that it works with symlinks

Changelog

Bug Fixes

• Fix check in HMI PTU logic to work with symlinks

CLA

• [x] I have signed the CLA