Add MS Teams webhook exposed key handling

[gjcthinkst]

Proposed changes

Add MS Teams webhook support for exposed API key alerts. While we're in the area also do some refactoring and general improvements for the MS Teams webhook.

Types of changes

What types of changes does your code introduce to this repository?

• New feature (non-breaking change which adds functionality)

Checklist

• Lint and unit tests pass locally with my changes (if applicable)
• I have run pre-commit (pre-commit in the repo)
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Linked to the relevant github issue or github discussion

Further comments

I tested the changes to the MS Teams webhook by creating a new AWS API key token, triggering it normally and manually creating an exposed key alert with CURL (with 25 Dec as the exposed time) and checked that all three MS Teams messages displayed correctly.

An example of the current (before this change) MS Teams message format is shown below.

[thinkst-tom]

@gjcthinkst It looks like we're using the legacy format here. There is a newer payload format using "Adaptive Cards".

Did you set up the webhook you used to test here with the Workflows app on MS Teams? Or with Connectors (doing it this way is going to be retired at some stage - MS is very vague about when though)?

[gjcthinkst]

@gjcthinkst It looks like we're using the legacy format here. There is a newer payload format using "Adaptive Cards".

Did you set up the webhook you used to test here with the Workflows app on MS Teams? Or with Connectors (doing it this way is going to be retired at some stage - MS is very vague about when though)?

@thinkst-tom I've had a quick look at the new format and the new Workflows app on MS Teams, but I think it's going to be a larger change to get the webhooks working with that. For this PR I think we should stick to the legacy format and connectors and leave the change to Workflows for a future PR.

[thinkst-tom]

I think we should stick to the legacy format and connectors and leave the change to Workflows for a future PR.

That sounds reasonable to me 👍