feat(unpinning): support unpinning a message via api

[rileylnapier]

Description

• create unpinMessage action
• add "onEvent" listener to know when events happen
• add more details to window.courier.inbox that has state and actions so embedded users can create actions
• add renewSession as an action to window.courier.renewSession

Type of change

• [ ] Bug fix (non-breaking change that fixes an issue)
• [x] New feature (non-breaking change that adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Related issues

Fix [#1]()

[linear[bot]]

C-9760 [Pinned] - Support unpinning a message

Create an unpin endpoint/mutation so we can unpin a message from an inbox

[codecov[bot]]

Codecov Report

:exclamation: No coverage uploaded for pull request base (main@216ed74). Click here to learn what that means. Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #457 +/- ## ======================================= Coverage ? 37.65% ======================================= Files ? 68 Lines ? 1126 Branches ? 336 ======================================= Hits ? 424 Misses ? 702 Partials ? 0 ```

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