…=weihanglo

Fix split-debuginfo support detection

### What does this PR try to resolve?
cargo assumed that if `-Csplit-debuginfo=packed` worked, all values would be correct. This however is not the case -- as of Rust 1.65.0, rustc supports `packed`, but not `unpacked` or `off` on Windows. Because of this, having `split-debuginfo="unpacked`" on Windows has caused builds to fail, as cargo assumed that the option is fine (`split-debuginfo=packed` worked), but rustc then failed when being passed `-Csplit-debuginfo=unpacked`.

### How should we test and review this PR?
Consider an empty project with the following change to `Cargo.toml`:
```toml
[profile.dev]
split-debuginfo="unpacked"
```
`cargo  1.64.0 build` will work, but `cargo  1.65.0 build` will fail with the following error message:

```
PS C:\REDACTED> cargo build
   Compiling tmp v0.1.0 (C:\REDACTED)
error: `-Csplit-debuginfo=unpacked` is unstable on this platform

error: could not compile `tmp` due to previous error
```

With this patch and 1.65.0 rustc, cargo will ignore all `split-debuginfo` settings, but with rust-lang/rust#104104 rustc (approved, awaiting merge), it will properly detect supported values for `split-debuginfo` and only ignore those that are unsupported.

…=ehuss

Reduce target info rustc query calls

test: Update for clap 4.1.3

The latest clap release fixed a bug with the algorithm for providing suggestions, leading this suggestion to change.

Temporarily pin libgit2-sys.

There are some issues with the most recent libgit2-sys 0.14.2 not working on Windows (libgit2/libgit2#6453 and libgit2/libgit2#6454). Until we figure out what to do with it, this pins the release to the previous version.

… r=epage

Disable network SSH tests on windows.

These tests have a high failure rate on Windows, so this disables them for now. I don't know exactly why they are failing. If I had to take a wild guess, I would suspect the use of WinCNG for the SSH backend, which may mean it is out of our control.