Add a toggle to break up tweets on words rather than punctuation

[marklocklear]

Add a toggle button for two options for how we split tweets. The two states are “Split at Punctuation” and “Split at word”. If we split at punctuation we split tweets at either . ! or ?. If we split at the work we just find 256 characters, then get the last full word. Also, I like the idea of adding “...” after the last word if that is the option they choose.

[marklocklear]

Added a mockup of this to figma.