Authenticate with email+accesstoken rather than email+password

[ghost]

Is your feature request related to a problem?

Settings-Sync allows to use my email and an access token I created specifically for settings-sync. Syncify doesn't support authentication via an access token. Instead it forwards me to either GitHub, GitLab, or Bitbucket where can only authorize Syncify but I can't limit what Syncify can do on my behalf. My GitHub account has become too important to grant unlimited access to Webhooks and services
and Deploy keys. Especially the deploy keys is very alarming to me.

Describe the solution you'd like

Add the possibility to accept email+accesstoken as authentication alternative for GitHub, GitLab, and BitBucket.

Describe alternatives you've considered

Alternatively remove the requirements to read deploy keys, Webhooks, etc.
Or instruct people to create another free GitHub, GitLab, BitBucket account which they exclusively use for Syncify.

Additional context

To sync settings you should only be caring about one repository either its public or private. You should not want to read my Deploy keys, nor my Webhook settings.