Add auto-split for Toots over character limit

[BDGreyson]

Is your feature request related to a problem? Please describe. Toots that are longer than the instance's character limit can (obviously) not be posted.

Describe the solution you'd like It would be lovely if Pachli could auto-split Toots that are too long for the instance into multiple Toots, separated either by word or by sentence so that the first Toot is created and the other parts are automatically created as replies/thread to each other.

Describe alternatives you've considered I can't really think about an alternative. My current way of handling it is manually cutting some content, hoping I intuitively cut enough to go below the limit, and then posting it as reply manually, hopefully between people interacted with the main Toot and are confused at its incompleteness.

Oh, or switching instances to one with higher character limit, but that would be a pity once you find a reall nicely fitting instance for yourself.