Linter rule (+ refactoring) to detect child resources and nest them within parent

**Is your feature request related to a problem? Please describe.**
Based on the note at the bottom of https://docs.microsoft.com/en-us/azure/azure-resource-manager/bicep/child-resource-name-type#full-resource-name-outside-parent, child resources should be bound to parents in a type-safe manner (either through nesting within the parent declaration or through explicit `parent:` keyword).

**Describe the solution you'd like**
Have a linter rule that detects the pattern of declaring children with a full resource type.

Read the linked Azure Bicep documentation on full resource names outside parents, then locate the linter and refactoring entry points for resource declarations. Define done as detecting child resources declared with a full resource type and offering nesting within the parent or an explicit parent: form, with coverage for both patterns.

Written by the indexing model from the issue text.