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 allows to use `gitoxide` for all fetch operations, boosting performance
for fetching the `crates.io` index by a factor of 2.2x, while being consistent
on all platforms.
For trying it, nightly builds of `cargo` can specify `-Zgitoxide=fetch`.
It's also possible to set the `__CARGO_USE_GITOXIDE_INSTEAD_OF_GIT2=1` environment
variable (value matters), which is when `-Zgitoxide=none` can be used
to use `git2` instead.
Limitations
-----------
Note that what follows are current shortcomings that will be addressed in future PRs.
- it's likely that authentication around the `ssh` protocol will work differently in practice
as it uses the `ssh` program.
- clones from `file://` based crates indices will need the `git` binary to serve the locatl repository.
- the progress bar shown when fetching doesn't work like the orgiinal, but should already feel 'faster'.
