Support for personal repository migrations from Azure DevOps

Hello! I have a few hundred repos in Azure DevOps that I'd like to migrate to GitHub however there is a dependency on having an Organization. I'd prefer these to be kept as personal repositories rather than filing them under an Organization.

I'm unfamiliar with Githubs Graph API so unsure if it's a requirement or just was built around an assumption of an organization (or perhaps it was previously paywalled?). Or, maybe it's Enterprise plans only?

Putting the username as the org-name doesn't work.

The `StartRepositoryMigrationInput` (https://docs.github.com/en/graphql/reference/input-objects#startrepositorymigrationinput) method appears to want the OwnerID (this script resolves from org name).

Is there anything stopping this from being a User/Personal ID?

### Ideal solution
- Adapt ado2gh parameters to accept a `--github-user` in place of a `--github-org`

### Possible workaround
- First migrate all repos to an Organization, then move them (individually 😰) from Organization to Personal?