Resolve bug with switching project on delete

[mrvisscher]

Updates to the project deletion workflow. Projects now get properly deleted. Notable changes:

• You can't delete your startup project anymore without first specifying another one in the settings. This reduces unexpected behaviour by AB.
• When a project is deleted, we first switch to said startup project to avoid "PermissionError"
• A succes/error dialogue is shown upon project deletion

Closes #1075

Demo

Checklist

• [x] Keep pull requests small so they can be easily reviewed.
• [x] Update the documentation, please follow the numpy style guide
• [ ] Update tests.
• [x] Categorize the PR by setting a good title and adding one of the labels: bug, feature, ui, change, documentation, breaking, ci as they show up in the changelog
• [x] Link this PR to related issues by using closing keywords.
• [x] Request a review from another developer.

[coveralls]

coverage: 50.033% (-0.02%) from 50.051% when pulling 3d889e68be90640f490b75d271961c473317e877 on mrvisscher:switch-on-project-delete into b4b1f74cae604219a5432d96d99c0825a12d1a96 on LCA-ActivityBrowser:master.

[github-actions[bot]]

This issue has been implemented in the new release of Activity Browser 🚀 (version 2.9.3), you can get the new version by updating Activity Browser.

🤖beep boop! I'm a bot and this message was an automated action. If updating does not make sense for this issue, just ignore this.