add periodic sync mode

[cstanislawski]

currently grafana-db-exporter only supports single docker run / cronjob (job) mode, it needs to be evaluated whether the continuous mode mode can be supported, i.e. we should periodically check for changes/track dashboards and upload any changes to the repo

this would have to support:

• adding changes to a new branch (the current, only supported, mode)
• adding changes to a single branch

Additionally to consider:

• adding changes directly to the "X" branch (e.g.: main) - seems like something that shouldn't be supported

mode name to be decided, proposals: proactive, reactive, continuous, stream, live, watch, dynamic

[cstanislawski]

having slept with it I think continuous mode is the most accurate & self-descriptive

[cstanislawski]

having thought about it I don't think it's worth implementing as the continuous mode would just go to sleep for most of the run time, so it'd be a cronjob that is running continuously

it'd also require architecture, whereas you can just run the exporter every h or so if you really need it

seems like an antipattern - closing

[cstanislawski]

I forgot that docker doesn't support cron-like functionality and people would have to jump through hoops to make it work

The point about this feature not being needed in terms of k8s clusters still stands though

[cstanislawski]

I think considering that most of the time the exporter will sleep, a better name for this mode will be periodic