feat: Update Datadog extract emails to slack playbook + add new transform actions

[daryllimyt]

Features

• Add depends_on validity checks
• dd strict flag for eval_jsonpath, defaults to false
• Add custom filter function as action and function expression.
  • This allows you to do more complex filtering, for example you can express these kinds of filtering semantics:
    • "filter a collection of items using a jsonpath pointing to a field in this item, and use a function/operator for evaluation/comparison"
• You can use double quotes for string literals
• Add dump run results to fs for debugging
• New actions
  • core.transfrom.filter: wrapper around custom_filter
  • core.transform.build_reference_table: Allows you to convert a list of objects into a dict, where you choose the key using a jsonpath
• Add time related function expressions: FN.now, FN.minutes
• Add workflow start_time into ENV context

Changes

• Allow validation to pass for jsonpath array syntax e.g. path[9]
• Updated DD playbook
• Rename slack_chatops secret back to slack

Testing

• All unit tests passing
• DD emails slack pb working live