Added new Bicep language features from v0.27.1 #2859 #2860 #2885

[BernieWhite]

PR Summary

• Added support for new Bicep language features introduced in v0.27.1.
  • Added support for shallowMerge, groupBy, objectKeys, and mapValues.
  • Updated syntax for Bicep lambda usage of map, reduce, and filter which now support indices.
  • Added support for spread operator.
• Fixed union does not perform deep merge or keep property order.

Fixes #2859
Fixes #2860
Fixes #2885

PR Checklist

• PR has a meaningful title
• Summarized changes
• Change is not breaking
• This PR is ready to merge and is not Work in Progress
• Other code changes
  • Unit tests created/ updated
  • Link to a filed issue
  • Change log has been updated with change under unreleased section