Incorrect support for @description decorator on keyword var

[SimonWahlin]

Bicep version
Bicep CLI version 0.9.1 (a2950a1)

Describe the bug
The decorator @description() is currently supported on the keyword var, it does not generate any warnings or errors but the description is not part of the compiled ARM template.

To Reproduce
Steps to reproduce the behavior:
The following bicep code will build successfully without errors or warnings:

@description('myVarDescription')
var descriptionVar = 'varHasDescription'

output varValue string = descriptionVar

The resulting ARM template does not contain the description myVarDescription

Additional context
Can we add a FunctionFlag for SupportsDescriptionDecorator or something similar?

This would also apply for the keyword metadata and possibly import

[alex-frankel]

Variables do not support description in ARM Templates, so this is by design. It still provides functionality (i.e. hovers) in bicep, so that's why it works and is allowed. If we feel it's critical, we can prioritize adding support for description in ARM templates.