[nx-cloud] Missing possibility to set env variables for GitHub VCS integration on frontend pods

[minijus]

Today frontend deployment template allows setting only explicit env values or directly from .env property in values.yaml (plain text, not good for secrets).

With this setup it is not possible to set required env variables for GitHub VCS integration from secret. Documentation defines a way to set these values, but the code does not seem to do it.

Proposed solutions:

1. Add support for envFrom. This would allow to set env from secrets or configMaps without a need to remap names in values.yaml
2. Add missing env values.