Deprecated decorator for module params

**Is your feature request related to a problem? Please describe.**
When developing module packs sometimes we need to remove a parameter (or replace it with a new one) , keeping old one for some time until users switch to new one.

**Describe the solution you'd like**
I'd like to have a `@deprecated('description')` decorator that I can place on parameter so bicep during compile time will throw warning and the VSCode extension will visually indicate on the module params that this one is deprecated - both in usages inside module and on value assignments.

Start by mapping how module parameters are declared and how compiler diagnostics reach both module consumers and the VSCode extension. Trace the parameter declaration and value-assignment paths, then determine how a deprecated annotation could produce warnings and visual indicators in both usages and assignments. Done means the requested decorator works at compile time and is represented in the extension as described.

Written by the indexing model from the issue text.