If movement commands don't find a target commit, they fail. However,
it's usually not intuitive why they fail because in non-edit mode the
start commit is the parent of the working commit.
Adding the start commit change hash to the error message makes it easier
for the user to figure out what is going on.
Also, specifying 'No **other** descendant...' helps make it clear what
`jj` is really looking for.
Part of #3947
* We started with a tristate flag where:
- Auto - Maintain current behaviour. This edits if
the wc parent is not a head commit. Else, it will
create a new commit on the parent of the wc in
the direction of movement.
- Always - Always edit
- Never - Never edit, prefer the new+squash workflow.
However, consensus the review thread is that `auto` mode where we try to infer when to
switch to `edit mode`, should be removed. So `ui.movement.edit` is a boolean flag now.
- true: edit mode
- false: new+squash mode
* Also add a `--no-edit` flag as the explicit inverse of `--edit` and
ensure both flags take precedence over the config.
* Update tests that assumed edit mode inference, to specify `--edit` explicitly.
NOTE: #4302 was squashed into this commit, so see that closed PR for review history.
Part of #3947
* Derive a bunch of standard and useful traits for `movement_util::Direction`
as it is a simple type. Importantly `Copy`.
* Return `&'static str` from Direction.cmd()
* Refactor out `MovementArgs` to reduce the number of arguments
to `movement_util::move_to_commit`.
* Implement `From<&NextArgs/&PrevArgs>` for MovementArgs
Part of #3947
The code in both cli/src/commands/{next,prev}.rs is identical except
for the direction of movement. This commit pull the parts that make
sense out into cli/src/movement_util.rs so it's easier to see the
differences.
Part of #3947
