Add the ability to un-take a shift swap request

[summerwollin]

What would you like to see!

Add the ability to un-take a shift swap request. We recently had an engineer accidentally take a swap request for the wrong shift and timezone and they now have to wait until the requesting engineer comes online on Monday and hope they delete the swap themselves. This means the engineer that accidentally took the swap will potentially be on-call during a time in which they cannot be available. Add the ability to un-take a shift swap, or for someone other than the requestor to be able to delete the shift swap.

Product Area

Schedules

Anything else to add?

No response

[github-actions]

The current version of Grafana OnCall, at the time this issue was opened, is v1.10.2. If your issue pertains to an older version of Grafana OnCall, please be sure to list it in the PR description. Thank you 😄!