CCM-13278: Confirm that we have received a file from a Trust

[gareth-allan]

Description

This PR adds the MESH Acknowledger component.

• Added a new mesh-acknowledge lambda
  • In Python, so that the mesh_client library can be used to send MESH messages
• Added component tests to verify the mesh-acknowledge lambda performs as expected
• Added a new meshMessageId field to the MESHInboxMessageDownloaded event
• Modified the event publisher library so that it can be used to publish events using the auto-generated types
  • This required a slight tweak to the way the types were generated in src/python-schema-generator
• Extracted the sender_lookup.py file added to the mesh-poll lambda in CCM-12616 mesh poll retrieve #104 to the sender-management package that currently contains the TypeScript sender management library
  • This is using the same approach as for the digital-letters-events package, where we have both TS and Python packages in a single directory
  • Extracted the package_python_lambda.sh script to utils

Context

Notify is documented as providing acknowledgement messages in response to MESH messages received. This provides confirmation that a request was successfully received. Since the integrator response is documented publicly, users of Digital Letters are likely to expect it, given they will be unaware that we’re operating within a bounded context that doesn’t include all of Core’s functionality, so we should implement the same functionality in Digital Letters.

Validation

To check that publishing directly to the DLQ works, I manually updated the configuration of the mesh-acknowledge lambda to set an incorrect event bridge ARN and event bridge DLQ URL and then used the Lambda's "test" function to send a valid message downloaded event. This resulted in the event publishing and DLQ-ing failing, and so the function pushed the record directly to the DLQ:

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

---

Sensitive Information Declaration

To ensure the utmost confidentiality and protect your and others privacy, we kindly ask you to NOT including PII (Personal Identifiable Information) / PID (Personal Identifiable Data) or any other sensitive data in this PR (Pull Request) and the codebase changes. We will remove any PR that do contain any sensitive information. We really appreciate your cooperation in this matter.

• I confirm that neither PII/PID nor sensitive data are included in this PR and the codebase changes.

[gareth-allan]

Just a couple of minor post-merge comments.

[Ian-Hodges]

I'm surprised the python event publisher is doing anything with mesh?

[simonlabarere]

It is now moved to a utility package for Python projects.

[simonlabarere]

See #186