Using project variable in secret property fields on DPC hybrid setup

Allowing a use of project variables for secret in component's password property. This is very important and highly needed when DPC setup is hybrid environment. 

In the case when using multiple environments (DEV, QA, PRD) over hybrid setup, multiple agents on different AWS VPN will be configured and every agent will have its own AWS secret for accessing sources for DEV, QA or PRD. The secrets on different agents cannot be mixed. Now, the secret has to be changed each time when pipelines are to be deployed (merged into the main branch linked with PRD agent after development and testing is done) on all source component if project variable that will hold different secret names for the different agent is not available.  

NOTE: Variable use was allowed for password property fields in ETL