Auto completion for Bicep registry (when an alias is configured) is missing required-properties

**Bicep version**
Bicep CLI version 0.13.1 (e3ac80d678)

**Describe the bug**
Auto completion is missing **required-properties**. This happens when an alias is configured for the Bicep registry.

Expected:

**To Reproduce**
Steps to reproduce the behavior:

**Additional context**
Add any other context about the problem here.

Start by reproducing the autocomplete behavior with a configured Bicep registry alias using Bicep CLI 0.13.1, comparing it with the expected completion shown in the issue. The fix is done when required properties appear in autocomplete for aliased registry references and the behavior is covered by an appropriate regression test.

Written by the indexing model from the issue text.