HM-763:Update subarraynode for arrayLayout

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

• Added 'arrayLayoutUri' attribute to store Array Layout URI and fetch data from TelModel.
• Updated 'assign_resource' command to accept URI and download array layout data.
• Updated 'configure' command to use downloaded array layout data and pass it to leaf nodes.
• Added unit and integration test case for the same.
• Updated RTD documentation for the newly added attribute.

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.