Add zed

[sethherr]

This PR adds support for the Zed text editor.

All submissions

• I have followed the Contributing Guidelines
• I have checked to ensure there aren't other open Pull Requests for the same update/change

Adding/updating Application X Support

• This PR is only for one application
• It has been added to the list of supported applications in the README
• Changes have been added to the WIP section of the CHANGELOG
• Syncing does not break the application
• Syncing does not compete with any syncing functionality internal to the application
• The configuration syncs the minimal set of data
• No file specific to the local workstation is synced
• No sensitive data is synced

Improving the Mackup codebase

• My submission passes the tests
• I have linted the code locally prior to submission
• I have written new tests as applicable
• I have added an explanation of what the changes do

[sethherr]

It doesn't seem like the failing markdown test is my fault? Not sure how to fix it

[lra]

Thanks!