Add support for long file paths in CheckoutOptions

[denis-kudelin]

Summary

Adds support for long file paths in CheckoutOptions by introducing the LongPaths property and updating CheckoutStrategy with the GIT_CHECKOUT_LONGPATHS flag.

Changes

• New property LongPaths in CheckoutOptions.
• Added GIT_CHECKOUT_LONGPATHS to CheckoutStrategy.

Motivation

Enhances compatibility with projects that have deeply nested directories or long file names, especially on Windows.

[DrewScoggins]

@bording could you take a look at this PR and help get it merged?

[Ogglas]

@bording We really need this bug fixed. Please prioritize it if possible

[LoopedBard3]

@Ogglas, I was able to workaround this by setting the longpath option in the global git config. Presuming a global git config already being present on the machine at %USERPROFILE%.gitconfig, we create a temp repo (new Repository(Repository.Init("temprepo"))) and then set the longpath setting in that global config with temp_repo.Config.Set("core.longpaths", true, ConfigurationLevel.Global);. With that set, the clone should use the global setting as long as it is not set at a more local level.

[bording]

As far as I can tell, this PR isn't actually doing anything. The support for long paths on Windows that was added to libgit2 in https://github.com/libgit2/libgit2/pull/5857 only supports the core.longpaths configuration setting.

Furthermore, the GIT_CHECKOUT_LONGPATHS setting that's been added to the CheckoutStrategy enum doesn't seem to exist at all in libgit2.

(1 << 24) is an entirely different option, GIT_CHECKOUT_DRY_RUN.

The good news is that LibGit2Sharp has been respecting the core.longpaths setting since at least 0.27.0, so you can already use long paths without needing any other changes.