Delete imported projects after user canceled import
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## Problem to solve
This issue is the second iteration of [Cancel project imports](https://gitlab.com/gitlab-org/gitlab/-/issues/247325/)
Currently, when a user imports projects into GitLab there is no way for them to cancel an import in-progress. The below scenario illustrates the problem:
#### Import all repositories
1. User authenticates their GitHub account. :slight_smile:
1. Selects "Import 234 repositories" from the `Import repositories from GitHub` page which initiates the import. :slight_smile:
1. User realizes they had made a mistake and needs to cancel their import and correct the error. :confused:
1. User finds no way to cancel the import. :rage:
1. User must go into GitLab project settings for each imported project and delete them manually. :weary:
This process is quite cumbersome and could cause a lot of frustration for the users.
In [this issue](https://gitlab.com/gitlab-org/gitlab/-/issues/247325/), we enabled `Cancel` option, but the data that already imported will be retained. In this issue we will enable `Delete` of the imported data.
### Proposal
Implement `Cancel and Delete` button.
* User can start the cancel process when an import is:
* Pending
* In progress
* User can't cancel after an import is complete.
* An import that is cancelled can not be resumed\*
* The cancel process has two outcomes:
* Cancel and retain — Importing stops, anything that has been imported stays in the project (implemented [here](https://gitlab.com/gitlab-org/gitlab/-/issues/247325/))
* Cancel and delete — Importing stops, anything that has been imported is deleted
* Users can choose the outcome — `cancel and retain` or `cancel and delete`.
| Example user flow |
| ------ |
|  |
| [Source](https://www.figma.com/file/lK3873uXEMUGmaC7nHkx5G/GitHub-Importer?node-id=2108%3A52354) |
The scope of this issue is for GitHub importer.
issue