[Enhancement] Constants ( Parameters ) For Resource Groups & Subscriptions

### Enhancement

Constant values that sit at either the resource group or subscription level which are immutable (_as in having GUID IDs_) that are addressable by the expression language..

Effectively adding a 'Parameter' that stretches across all resources that can address it via expression or directly.

### Which Logic App type(s) should this apply to?

Both

The issue names no files, tests, or entry points. Start by locating the expression-language and resource-scope handling in the Logic Apps code, then clarify the design for immutable resource-group and subscription constants, including how both Logic App types address them and what tests would demonstrate completion.

Written by the indexing model from the issue text.