When cycling history, we want to make it so that upon returning to the original prompt, you get your text back.
Importantly, we don't want to use the existing preservedMessage field for that because that's only for preserving
a NEW commit message, and we don't want the history stuff of the commit reword flow to overwrite that.
When we use the one panel for the entire commit message, its tricky to have a keybinding both for adding a newline and submitting.
By having two panels: one for the summary line and one for the description, we allow for 'enter' to submit the message when done from the summary panel,
and 'enter' to add a newline when done from the description panel. Alt-enter, for those who can use that key combo, also works for submitting the message
from the description panel. For those who can't use that key combo, and don't want to remap the keybinding, they can hit tab to go back to the summary panel
and then 'enter' to submit the message.
We have some awkwardness in that both contexts (i.e. panels) need to appear and disappear in tandem and we don't have a great way of handling that concept,
so we just push both contexts one after the other, and likewise remove both contexts when we escape.
We already have this very convenient behavior of jumping to the next stageable
line after staging something. However, while this worked well for staging
single lines or hunks, it didn't work correctly when staging a range of lines;
in this case we want to start searching from the first line of the range.
While we try to keep the view's cursor position in sync with the context state's
selectedLineIdx (at least when pressing up or down), there are enough situations
where the two run out of sync; for example when initially opening the view, or
after staging a hunk, or when scrolling the view using the wheel. While it would
be possible to fix these situations to keep them always in sync, it doesn't seem
worth it, because the view's cursor position isn't really used for anything
else. So we rather special-case the SelectedLine/SelectedLineIdx functions of
ViewDriver to query the context state's selectedLineIdx directly if it is a
patch explorer context.
