Support disabling startup at login

[lorin]

Each time I run corectl.app, it adds itself as a login item so that it automatically starts up the next time I log in. I'd like to be able to disable this behavior.

[rimusz]

that is planned at some point of time, need first to implement the Preferences where different options can be set. it is time consuming for me.
So I just did a small hack around for now

[franz-josef-kaiser]

@rimusz We all suffer from too less time for side projects. Can you point to the file and line (best: a blob link) where this feature could be added? And would you consider a multi-stepped plan? If yes: How would that look like? Maybe we can lend a helping hand?

[rimusz]

done in https://github.com/TheNewNormal/corectl.app/releases/tag/v0.2.9