feat: #3586997 Allow the access token to be pulled from settings

Phil Nortonrequested to merge
issue/mastodon_api-3586997:3586997-allow-the-access into 1.0.x

Refactored the MastodonApiInstanceInterface to be in the same directory as the MastodonApiInstance class. Added a test for the state/settings instance access token override. One or two minior code formatting changes.

By: philipnorton42

Closes #3586997

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