Google chat cards

[elliotmatson]

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Description

Adds card-based messages to Google Chat for more streamlined notifications

Type of change

Please delete any options that are not relevant.

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

Checklist

• My code follows the style guidelines of this project
• I ran ESLint and other linters for modified files
• I have performed a self-review of my own code and tested it
• I have commented my code, particularly in hard-to-understand areas
  (including JSDoc for methods)
• My changes generate no new warnings
• My code needed automated testing. I have added them (this is optional task)

Screenshots

[CommanderStorm]

Overall, this looks good to go.
I have left some minor comments.

Could you add a screenshot of the before state?

[elliotmatson]

Thanks! Good catches!

Here's before:

[CommanderStorm]

Thanks for the enhancement!

All changes in this PR are small and uncontroversial
⇒ merging with junior maintainer approval (despite this being in a future merge-slot)