improve inline type property decorator completion logic and add tests

[polatengin]

Fixes #16942

Description

Fix decorator completions for properties inside inline object types (for example, param foo { @| name: string }) to suggest decorators based on the property's type rather than the enclosing declaration's type.

Example Usage

Before this fix, typing @ on an inline object type property would show incomplete completions:

param clusterSettings {
  @  // Previously suggested `@sealed`, `@discriminator` (object-level)
  name: string
}

With this PR, completions align with the property's type;

param clusterSettings {
  @  // Now suggests `@minLength`, `@maxLength`, `@description`, `@metadata` (string-level)
  name: string
}

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 23091409924)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 23091409924

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 23091409924"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 23091409924

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 23091409924"