This is for `cargo generate-lockfile` and when syncing the lockfile with
the manifest.
We still show it for `cargo update` because of `cargo update
--workspace`.
We hacked around this previously by filtering out the `num_pkgs==1` case
for single packages but this didn't help with workspaces.
This is to help with #9930
Example changes:
```diff
-[LOCKING] 4 packages
+[LOCKING] 4 packages to latest version
-[LOCKING] 2 packages
+[LOCKING] 2 packages to latest Rust 1.60.0 compatible versions
-[LOCKING] 2 packages
+[LOCKING] 2 packages to earliest versions
```
Benefits
- The package count is of "added" packages and this makes that more
logically clear
- This gives users transparency into what is happening, especially with
- what rust-version is use
- the transition to this feature in the new edition
- whether the planned config was applied or not (as I don't want it to
require an MSRV bump)
- Will make it easier in tests to show what changed
- Provides more motiviation to show this message in `cargo update` and
`cargo install` (that will be explored in a follow up PR)
This does come at the cost of more verbose output but hopefully not too
verbose. This is why I left off other factors, like avoid-dev-deps.
This uses a new feature from snapbox that let's us render terminal
styling in SVG files. This let's us see / visualize ANSI escape codes,
including in github's UI (will render images, including side-by-side
images for diffs).
