Add paragraph to helix bracket menus

[jgdhs27]

Add 'Goto next paragraph' and 'Goto previous paragraph' to helix, under the keybinds [p and ]p.

[71]

Thank you!

[jgdhs27]

I've made the suggested changes. However, I noticed some issues with the paragraph selection that only occur with
"selectionBehavior": "character" - see #408. I think that most users will be using this selection mode with helix, so I think it would make sense to look for a fix to that before merging this.

[71]

Thank you!