HM-387: Loading dish vcc config during initialization

1. What this MR does / why we need it:

• Implementation done to load dish vcc config during TMC initialization
• DishVccURI and DishVCCFilePath property added to central node
• TelescopeState set to UNKNOWN if dish vcc config not set
• Updated commandNotAllowed method such that if dish vcc config is not set then TMC operation not allowed

2. Make sure that you've checked the boxes below before you submit MR:

• No conflict with master branch.
• Merge Request Title appropriate.
• Unit/Integration tests added and existing test cases are passing.
• Variable and Function names state the purpose.
• There is no commented out code, print/debug statements.
• Logs are added wherever necessary.
• Exception is handled wherever required.